Merge webkit.org at r50258 : Initial merge by git.

Change-Id: I1a9e1dc4ed654b69174ad52a4f031a07240f37b0

60 files changed, 686 insertions, 615 deletions

diff --git a/JavaScriptCore/runtime/Arguments.h b/JavaScriptCore/runtime/Arguments.h
index 5be84a2..9b674a2 100644
--- a/JavaScriptCore/runtime/Arguments.h
+++ b/JavaScriptCore/runtime/Arguments.h
@@ -85,9 +85,12 @@ namespace JSC {
 
         static PassRefPtr<Structure> createStructure(JSValue prototype) 
         { 
-            return Structure::create(prototype, TypeInfo(ObjectType)); 
+            return Structure::create(prototype, TypeInfo(ObjectType, StructureFlags)); 
         }
 
+    protected:
+        static const unsigned StructureFlags = OverridesGetOwnPropertySlot | OverridesMarkChildren | OverridesGetPropertyNames | JSObject::StructureFlags;
+
     private:
         void getArgumentsData(CallFrame*, JSFunction*&, ptrdiff_t& firstParameterIndex, Register*& argv, int& argc);
         virtual bool getOwnPropertySlot(ExecState*, const Identifier& propertyName, PropertySlot&);
diff --git a/JavaScriptCore/runtime/ArrayConstructor.cpp b/JavaScriptCore/runtime/ArrayConstructor.cpp
index 0237fd4..fb44494 100644
--- a/JavaScriptCore/runtime/ArrayConstructor.cpp
+++ b/JavaScriptCore/runtime/ArrayConstructor.cpp
@@ -50,7 +50,7 @@ ArrayConstructor::ArrayConstructor(ExecState* exec, NonNullPassRefPtr<Structure>
     putDirectFunctionWithoutTransition(exec, new (exec) NativeFunctionWrapper(exec, prototypeFunctionStructure, 1, exec->propertyNames().isArray, arrayConstructorIsArray), DontEnum);
 }
 
-static JSObject* constructArrayWithSizeQuirk(ExecState* exec, const ArgList& args)
+static inline JSObject* constructArrayWithSizeQuirk(ExecState* exec, const ArgList& args)
 {
     // a single numeric argument denotes the array size (!)
     if (args.size() == 1 && args.at(0).isNumber()) {
diff --git a/JavaScriptCore/runtime/BooleanObject.h b/JavaScriptCore/runtime/BooleanObject.h
index 28f796a..69c2e51 100644
--- a/JavaScriptCore/runtime/BooleanObject.h
+++ b/JavaScriptCore/runtime/BooleanObject.h
@@ -34,7 +34,7 @@ namespace JSC {
         
         static PassRefPtr<Structure> createStructure(JSValue prototype)
         {
-            return Structure::create(prototype, TypeInfo(ObjectType, HasStandardGetOwnPropertySlot | HasDefaultMark | HasDefaultGetPropertyNames));
+            return Structure::create(prototype, TypeInfo(ObjectType, StructureFlags));
         }
     };
 
diff --git a/JavaScriptCore/runtime/Collector.cpp b/JavaScriptCore/runtime/Collector.cpp
index 1a5eb89..1b238d9 100644
--- a/JavaScriptCore/runtime/Collector.cpp
+++ b/JavaScriptCore/runtime/Collector.cpp
@@ -1228,6 +1228,10 @@ static const char* typeName(JSCell* cell)
 #endif
     if (cell->isGetterSetter())
         return "gettersetter";
+    if (cell->isAPIValueWrapper())
+        return "value wrapper";
+    if (cell->isPropertyNameIterator())
+        return "for-in iterator";
     ASSERT(cell->isObject());
     const ClassInfo* info = cell->classInfo();
     return info ? info->className : "Object";
diff --git a/JavaScriptCore/runtime/Collector.h b/JavaScriptCore/runtime/Collector.h
index 2ce13dc..9ca9d18 100644
--- a/JavaScriptCore/runtime/Collector.h
+++ b/JavaScriptCore/runtime/Collector.h
@@ -71,14 +71,6 @@ namespace JSC {
 
         void destroy();
 
-#ifdef JAVASCRIPTCORE_BUILDING_ALL_IN_ONE_FILE
-        // We can inline these functions because everything is compiled as
-        // one file, so the heapAllocate template definitions are available.
-        // However, allocateNumber is used via jsNumberCell outside JavaScriptCore.
-        // Thus allocateNumber needs to provide a non-inline version too.
-        void* inlineAllocateNumber(size_t s) { return heapAllocate<NumberHeap>(s); }
-        void* inlineAllocate(size_t s) { return heapAllocate<PrimaryHeap>(s); }
-#endif
         void* allocateNumber(size_t);
         void* allocate(size_t);
 
diff --git a/JavaScriptCore/runtime/DateConstructor.cpp b/JavaScriptCore/runtime/DateConstructor.cpp
index f9b7d84..9908fef 100644
--- a/JavaScriptCore/runtime/DateConstructor.cpp
+++ b/JavaScriptCore/runtime/DateConstructor.cpp
@@ -112,9 +112,7 @@ JSObject* constructDate(ExecState* exec, const ArgList& args)
         }
     }
 
-    DateInstance* result = new (exec) DateInstance(exec->lexicalGlobalObject()->dateStructure());
-    result->setInternalValue(jsNumber(exec, timeClip(value)));
-    return result;
+    return new (exec) DateInstance(exec, value);
 }
     
 static JSObject* constructWithDateConstructor(ExecState* exec, JSObject*, const ArgList& args)
diff --git a/JavaScriptCore/runtime/DateInstance.cpp b/JavaScriptCore/runtime/DateInstance.cpp
index 4cd58f5..d4c9ef7 100644
--- a/JavaScriptCore/runtime/DateInstance.cpp
+++ b/JavaScriptCore/runtime/DateInstance.cpp
@@ -32,95 +32,43 @@ using namespace WTF;
 
 namespace JSC {
 
-struct DateInstance::Cache {
-    double m_gregorianDateTimeCachedForMS;
-    GregorianDateTime m_cachedGregorianDateTime;
-    double m_gregorianDateTimeUTCCachedForMS;
-    GregorianDateTime m_cachedGregorianDateTimeUTC;
-};
-
 const ClassInfo DateInstance::info = {"Date", 0, 0, 0};
 
-DateInstance::DateInstance(NonNullPassRefPtr<Structure> structure)
+DateInstance::DateInstance(ExecState* exec, NonNullPassRefPtr<Structure> structure)
     : JSWrapperObject(structure)
-    , m_cache(0)
 {
+    setInternalValue(jsNaN(exec));
 }
 
 DateInstance::DateInstance(ExecState* exec, double time)
     : JSWrapperObject(exec->lexicalGlobalObject()->dateStructure())
-    , m_cache(0)
 {
     setInternalValue(jsNumber(exec, timeClip(time)));
 }
 
-DateInstance::~DateInstance()
+bool DateInstance::getGregorianDateTime(ExecState* exec, bool outputIsUTC, GregorianDateTime& t) const
 {
-    delete m_cache;
-}
+    double milli = internalNumber();
+    if (isnan(milli))
+        return false;
 
-void DateInstance::msToGregorianDateTime(double milli, bool outputIsUTC, GregorianDateTime& t) const
-{
-    if (!m_cache) {
-        m_cache = new Cache;
-        m_cache->m_gregorianDateTimeCachedForMS = NaN;
-        m_cache->m_gregorianDateTimeUTCCachedForMS = NaN;
-    }
+    if (!m_data)
+        m_data = exec->globalData().dateInstanceCache.add(milli);
 
     if (outputIsUTC) {
-        if (m_cache->m_gregorianDateTimeUTCCachedForMS != milli) {
-            WTF::msToGregorianDateTime(milli, true, m_cache->m_cachedGregorianDateTimeUTC);
-            m_cache->m_gregorianDateTimeUTCCachedForMS = milli;
+        if (m_data->m_gregorianDateTimeUTCCachedForMS != milli) {
+            WTF::msToGregorianDateTime(internalNumber(), true, m_data->m_cachedGregorianDateTimeUTC);
+            m_data->m_gregorianDateTimeUTCCachedForMS = milli;
         }
-        t.copyFrom(m_cache->m_cachedGregorianDateTimeUTC);
+        t.copyFrom(m_data->m_cachedGregorianDateTimeUTC);
     } else {
-        if (m_cache->m_gregorianDateTimeCachedForMS != milli) {
-            WTF::msToGregorianDateTime(milli, false, m_cache->m_cachedGregorianDateTime);
-            m_cache->m_gregorianDateTimeCachedForMS = milli;
+        if (m_data->m_gregorianDateTimeCachedForMS != milli) {
+            WTF::msToGregorianDateTime(internalNumber(), false, m_data->m_cachedGregorianDateTime);
+            m_data->m_gregorianDateTimeCachedForMS = milli;
         }
-        t.copyFrom(m_cache->m_cachedGregorianDateTime);
+        t.copyFrom(m_data->m_cachedGregorianDateTime);
     }
-}
 
-bool DateInstance::getTime(GregorianDateTime& t, int& offset) const
-{
-    double milli = internalNumber();
-    if (isnan(milli))
-        return false;
-    
-    msToGregorianDateTime(milli, false, t);
-    offset = gmtoffset(t);
-    return true;
-}
-
-bool DateInstance::getUTCTime(GregorianDateTime& t) const
-{
-    double milli = internalNumber();
-    if (isnan(milli))
-        return false;
-    
-    msToGregorianDateTime(milli, true, t);
-    return true;
-}
-
-bool DateInstance::getTime(double& milli, int& offset) const
-{
-    milli = internalNumber();
-    if (isnan(milli))
-        return false;
-    
-    GregorianDateTime t;
-    msToGregorianDateTime(milli, false, t);
-    offset = gmtoffset(t);
-    return true;
-}
-
-bool DateInstance::getUTCTime(double& milli) const
-{
-    milli = internalNumber();
-    if (isnan(milli))
-        return false;
-    
     return true;
 }
 
diff --git a/JavaScriptCore/runtime/DateInstance.h b/JavaScriptCore/runtime/DateInstance.h
index 36d90b1..38b321c 100644
--- a/JavaScriptCore/runtime/DateInstance.h
+++ b/JavaScriptCore/runtime/DateInstance.h
@@ -32,27 +32,26 @@ namespace JSC {
     class DateInstance : public JSWrapperObject {
     public:
         DateInstance(ExecState*, double);
-        explicit DateInstance(NonNullPassRefPtr<Structure>);
-        virtual ~DateInstance();
+        explicit DateInstance(ExecState*, NonNullPassRefPtr<Structure>);
 
         double internalNumber() const { return internalValue().uncheckedGetNumber(); }
 
-        bool getTime(WTF::GregorianDateTime&, int& offset) const;
-        bool getUTCTime(WTF::GregorianDateTime&) const;
-        bool getTime(double& milliseconds, int& offset) const;
-        bool getUTCTime(double& milliseconds) const;
-
         static JS_EXPORTDATA const ClassInfo info;
 
-        void msToGregorianDateTime(double, bool outputIsUTC, WTF::GregorianDateTime&) const;
+        bool getGregorianDateTime(ExecState*, bool outputIsUTC, WTF::GregorianDateTime&) const;
+
+        static PassRefPtr<Structure> createStructure(JSValue prototype)
+        {
+            return Structure::create(prototype, TypeInfo(ObjectType, StructureFlags));
+        }
+
+    protected:
+        static const unsigned StructureFlags = OverridesMarkChildren | JSWrapperObject::StructureFlags;
 
     private:
         virtual const ClassInfo* classInfo() const { return &info; }
 
-        using JSWrapperObject::internalValue;
-
-        struct Cache;
-        mutable Cache* m_cache;
+        mutable RefPtr<DateInstanceData> m_data;
     };
 
     DateInstance* asDateInstance(JSValue);
diff --git a/JavaScriptCore/runtime/DateInstanceCache.h b/JavaScriptCore/runtime/DateInstanceCache.h
new file mode 100644
index 0000000..b626c1d
--- /dev/null
+++ b/JavaScriptCore/runtime/DateInstanceCache.h
@@ -0,0 +1,89 @@
+/*
+ * Copyright (C) 2009 Apple Inc. All Rights Reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef DateInstanceCache_h
+#define DateInstanceCache_h
+
+#include <wtf/DateMath.h>
+#include <wtf/HashFunctions.h>
+#include <wtf/PassRefPtr.h>
+#include <wtf/RefCounted.h>
+
+namespace JSC {
+
+    extern const double NaN;
+
+    class DateInstanceData : public RefCounted<DateInstanceData> {
+    public:
+        static PassRefPtr<DateInstanceData> create() { return adoptRef(new DateInstanceData); }
+
+        double m_gregorianDateTimeCachedForMS;
+        WTF::GregorianDateTime m_cachedGregorianDateTime;
+        double m_gregorianDateTimeUTCCachedForMS;
+        WTF::GregorianDateTime m_cachedGregorianDateTimeUTC;
+
+    private:
+        DateInstanceData()
+            : m_gregorianDateTimeCachedForMS(NaN)
+            , m_gregorianDateTimeUTCCachedForMS(NaN)
+        {
+        }
+    };
+
+    class DateInstanceCache {
+    public:
+        DateInstanceCache()
+        {
+            for (size_t i = 0; i < cacheSize; ++i)
+                m_cache[i].key = NaN;
+        }
+        
+        DateInstanceData* add(double d)
+        {
+            CacheEntry& entry = lookup(d);
+            if (d == entry.key)
+                return entry.value.get();
+
+            entry.key = d;
+            entry.value = DateInstanceData::create();
+            return entry.value.get();
+        }
+
+    private:
+        static const size_t cacheSize = 64;
+
+        struct CacheEntry {
+            double key;
+            RefPtr<DateInstanceData> value;
+        };
+
+        CacheEntry& lookup(double d) { return m_cache[WTF::FloatHash<double>::hash(d) & (cacheSize - 1)]; }
+
+        CacheEntry m_cache[cacheSize];
+    };
+
+} // namespace JSC
+
+#endif // DateInstanceCache_h
diff --git a/JavaScriptCore/runtime/DatePrototype.cpp b/JavaScriptCore/runtime/DatePrototype.cpp
index e46ab67..3f3e1f9 100644
--- a/JavaScriptCore/runtime/DatePrototype.cpp
+++ b/JavaScriptCore/runtime/DatePrototype.cpp
@@ -251,11 +251,12 @@ static JSCell* formatLocaleDate(ExecState* exec, const GregorianDateTime& gdt, L
     return jsNontrivialString(exec, timebuffer);
 }
 
-static JSCell* formatLocaleDate(ExecState* exec, DateInstance* dateObject, double timeInMilliseconds, LocaleDateTimeFormat format, const ArgList&)
+static JSCell* formatLocaleDate(ExecState* exec, DateInstance* dateObject, double, LocaleDateTimeFormat format, const ArgList&)
 {
     GregorianDateTime gregorianDateTime;
-    const bool notUTC = false;
-    dateObject->msToGregorianDateTime(timeInMilliseconds, notUTC, gregorianDateTime);
+    const bool outputIsUTC = false;
+    if (!dateObject->getGregorianDateTime(exec, outputIsUTC, gregorianDateTime))
+        return jsNontrivialString(exec, "Invalid Date");
     return formatLocaleDate(exec, gregorianDateTime, format);
 }
 
@@ -396,9 +397,8 @@ const ClassInfo DatePrototype::info = {"Date", &DateInstance::info, 0, ExecState
 // ECMA 15.9.4
 
 DatePrototype::DatePrototype(ExecState* exec, NonNullPassRefPtr<Structure> structure)
-    : DateInstance(structure)
+    : DateInstance(exec, structure)
 {
-    setInternalValue(jsNaN(exec));
     // The constructor will be added later, after DateConstructor has been built.
 }
 
@@ -420,16 +420,14 @@ JSValue JSC_HOST_CALL dateProtoFuncToString(ExecState* exec, JSObject*, JSValue
     if (!thisValue.inherits(&DateInstance::info))
         return throwError(exec, TypeError);
 
-    const bool utc = false;
+    const bool outputIsUTC = false;
 
     DateInstance* thisDateObj = asDateInstance(thisValue); 
-    double milli = thisDateObj->internalNumber();
-    if (isnan(milli))
-        return jsNontrivialString(exec, "Invalid Date");
 
     GregorianDateTime t;
-    thisDateObj->msToGregorianDateTime(milli, utc, t);
-    return jsNontrivialString(exec, formatDate(t) + " " + formatTime(t, utc));
+    if (!thisDateObj->getGregorianDateTime(exec, outputIsUTC, t))
+        return jsNontrivialString(exec, "Invalid Date");
+    return jsNontrivialString(exec, formatDate(t) + " " + formatTime(t, outputIsUTC));
 }
 
 JSValue JSC_HOST_CALL dateProtoFuncToUTCString(ExecState* exec, JSObject*, JSValue thisValue, const ArgList&)
@@ -437,16 +435,14 @@ JSValue JSC_HOST_CALL dateProtoFuncToUTCString(ExecState* exec, JSObject*, JSVal
     if (!thisValue.inherits(&DateInstance::info))
         return throwError(exec, TypeError);
 
-    const bool utc = true;
+    const bool outputIsUTC = true;
 
     DateInstance* thisDateObj = asDateInstance(thisValue); 
-    double milli = thisDateObj->internalNumber();
-    if (isnan(milli))
-        return jsNontrivialString(exec, "Invalid Date");
 
     GregorianDateTime t;
-    thisDateObj->msToGregorianDateTime(milli, utc, t);
-    return jsNontrivialString(exec, formatDateUTCVariant(t) + " " + formatTime(t, utc));
+    if (!thisDateObj->getGregorianDateTime(exec, outputIsUTC, t))
+        return jsNontrivialString(exec, "Invalid Date");
+    return jsNontrivialString(exec, formatDateUTCVariant(t) + " " + formatTime(t, outputIsUTC));
 }
 
 JSValue JSC_HOST_CALL dateProtoFuncToISOString(ExecState* exec, JSObject*, JSValue thisValue, const ArgList&)
@@ -454,19 +450,17 @@ JSValue JSC_HOST_CALL dateProtoFuncToISOString(ExecState* exec, JSObject*, JSVal
     if (!thisValue.inherits(&DateInstance::info))
         return throwError(exec, TypeError);
     
-    const bool utc = true;
+    const bool outputIsUTC = true;
     
     DateInstance* thisDateObj = asDateInstance(thisValue); 
-    double milli = thisDateObj->internalNumber();
-    if (!isfinite(milli))
-        return jsNontrivialString(exec, "Invalid Date");
     
     GregorianDateTime t;
-    thisDateObj->msToGregorianDateTime(milli, utc, t);
+    if (!thisDateObj->getGregorianDateTime(exec, outputIsUTC, t))
+        return jsNontrivialString(exec, "Invalid Date");
     // Maximum amount of space we need in buffer: 6 (max. digits in year) + 2 * 5 (2 characters each for month, day, hour, minute, second) + 4 (. + 3 digits for milliseconds)
     // 6 for formatting and one for null termination = 27.  We add one extra character to allow us to force null termination.
     char buffer[28];
-    snprintf(buffer, sizeof(buffer) - 1, "%04d-%02d-%02dT%02d:%02d:%02d.%03dZ", 1900 + t.year, t.month + 1, t.monthDay, t.hour, t.minute, t.second, static_cast<int>(fmod(milli, 1000)));
+    snprintf(buffer, sizeof(buffer) - 1, "%04d-%02d-%02dT%02d:%02d:%02d.%03dZ", 1900 + t.year, t.month + 1, t.monthDay, t.hour, t.minute, t.second, static_cast<int>(fmod(thisDateObj->internalNumber(), 1000)));
     buffer[sizeof(buffer) - 1] = 0;
     return jsNontrivialString(exec, buffer);
 }
@@ -476,15 +470,13 @@ JSValue JSC_HOST_CALL dateProtoFuncToDateString(ExecState* exec, JSObject*, JSVa
     if (!thisValue.inherits(&DateInstance::info))
         return throwError(exec, TypeError);
 
-    const bool utc = false;
+    const bool outputIsUTC = false;
 
     DateInstance* thisDateObj = asDateInstance(thisValue); 
-    double milli = thisDateObj->internalNumber();
-    if (isnan(milli))
-        return jsNontrivialString(exec, "Invalid Date");
 
     GregorianDateTime t;
-    thisDateObj->msToGregorianDateTime(milli, utc, t);
+    if (!thisDateObj->getGregorianDateTime(exec, outputIsUTC, t))
+        return jsNontrivialString(exec, "Invalid Date");
     return jsNontrivialString(exec, formatDate(t));
 }
 
@@ -493,16 +485,14 @@ JSValue JSC_HOST_CALL dateProtoFuncToTimeString(ExecState* exec, JSObject*, JSVa
     if (!thisValue.inherits(&DateInstance::info))
         return throwError(exec, TypeError);
 
-    const bool utc = false;
+    const bool outputIsUTC = false;
 
     DateInstance* thisDateObj = asDateInstance(thisValue); 
-    double milli = thisDateObj->internalNumber();
-    if (isnan(milli))
-        return jsNontrivialString(exec, "Invalid Date");
 
     GregorianDateTime t;
-    thisDateObj->msToGregorianDateTime(milli, utc, t);
-    return jsNontrivialString(exec, formatTime(t, utc));
+    if (!thisDateObj->getGregorianDateTime(exec, outputIsUTC, t))
+        return jsNontrivialString(exec, "Invalid Date");
+    return jsNontrivialString(exec, formatTime(t, outputIsUTC));
 }
 
 JSValue JSC_HOST_CALL dateProtoFuncToLocaleString(ExecState* exec, JSObject*, JSValue thisValue, const ArgList& args)
@@ -511,11 +501,7 @@ JSValue JSC_HOST_CALL dateProtoFuncToLocaleString(ExecState* exec, JSObject*, JS
         return throwError(exec, TypeError);
 
     DateInstance* thisDateObj = asDateInstance(thisValue); 
-    double milli = thisDateObj->internalNumber();
-    if (isnan(milli))
-        return jsNontrivialString(exec, "Invalid Date");
-
-    return formatLocaleDate(exec, thisDateObj, milli, LocaleDateAndTime, args);
+    return formatLocaleDate(exec, thisDateObj, thisDateObj->internalNumber(), LocaleDateAndTime, args);
 }
 
 JSValue JSC_HOST_CALL dateProtoFuncToLocaleDateString(ExecState* exec, JSObject*, JSValue thisValue, const ArgList& args)
@@ -524,11 +510,7 @@ JSValue JSC_HOST_CALL dateProtoFuncToLocaleDateString(ExecState* exec, JSObject*
         return throwError(exec, TypeError);
 
     DateInstance* thisDateObj = asDateInstance(thisValue); 
-    double milli = thisDateObj->internalNumber();
-    if (isnan(milli))
-        return jsNontrivialString(exec, "Invalid Date");
-
-    return formatLocaleDate(exec, thisDateObj, milli, LocaleDate, args);
+    return formatLocaleDate(exec, thisDateObj, thisDateObj->internalNumber(), LocaleDate, args);
 }
 
 JSValue JSC_HOST_CALL dateProtoFuncToLocaleTimeString(ExecState* exec, JSObject*, JSValue thisValue, const ArgList& args)
@@ -537,11 +519,7 @@ JSValue JSC_HOST_CALL dateProtoFuncToLocaleTimeString(ExecState* exec, JSObject*
         return throwError(exec, TypeError);
 
     DateInstance* thisDateObj = asDateInstance(thisValue); 
-    double milli = thisDateObj->internalNumber();
-    if (isnan(milli))
-        return jsNontrivialString(exec, "Invalid Date");
-
-    return formatLocaleDate(exec, thisDateObj, milli, LocaleTime, args);
+    return formatLocaleDate(exec, thisDateObj, thisDateObj->internalNumber(), LocaleTime, args);
 }
 
 JSValue JSC_HOST_CALL dateProtoFuncGetTime(ExecState* exec, JSObject*, JSValue thisValue, const ArgList&)
@@ -549,12 +527,7 @@ JSValue JSC_HOST_CALL dateProtoFuncGetTime(ExecState* exec, JSObject*, JSValue t
     if (!thisValue.inherits(&DateInstance::info))
         return throwError(exec, TypeError);
 
-    DateInstance* thisDateObj = asDateInstance(thisValue); 
-    double milli = thisDateObj->internalNumber();
-    if (isnan(milli))
-        return jsNaN(exec);
-
-    return jsNumber(exec, milli);
+    return asDateInstance(thisValue)->internalValue(); 
 }
 
 JSValue JSC_HOST_CALL dateProtoFuncGetFullYear(ExecState* exec, JSObject*, JSValue thisValue, const ArgList&)
@@ -562,15 +535,13 @@ JSValue JSC_HOST_CALL dateProtoFuncGetFullYear(ExecState* exec, JSObject*, JSVal
     if (!thisValue.inherits(&DateInstance::info))
         return throwError(exec, TypeError);
 
-    const bool utc = false;
+    const bool outputIsUTC = false;
 
     DateInstance* thisDateObj = asDateInstance(thisValue); 
-    double milli = thisDateObj->internalNumber();
-    if (isnan(milli))
-        return jsNaN(exec);
 
     GregorianDateTime t;
-    thisDateObj->msToGregorianDateTime(milli, utc, t);
+    if (!thisDateObj->getGregorianDateTime(exec, outputIsUTC, t))
+        return jsNaN(exec);
     return jsNumber(exec, 1900 + t.year);
 }
 
@@ -579,15 +550,13 @@ JSValue JSC_HOST_CALL dateProtoFuncGetUTCFullYear(ExecState* exec, JSObject*, JS
     if (!thisValue.inherits(&DateInstance::info))
         return throwError(exec, TypeError);
 
-    const bool utc = true;
+    const bool outputIsUTC = true;
 
     DateInstance* thisDateObj = asDateInstance(thisValue); 
-    double milli = thisDateObj->internalNumber();
-    if (isnan(milli))
-        return jsNaN(exec);
 
     GregorianDateTime t;
-    thisDateObj->msToGregorianDateTime(milli, utc, t);
+    if (!thisDateObj->getGregorianDateTime(exec, outputIsUTC, t))
+        return jsNaN(exec);
     return jsNumber(exec, 1900 + t.year);
 }
 
@@ -596,16 +565,14 @@ JSValue JSC_HOST_CALL dateProtoFuncToGMTString(ExecState* exec, JSObject*, JSVal
     if (!thisValue.inherits(&DateInstance::info))
         return throwError(exec, TypeError);
 
-    const bool utc = true;
+    const bool outputIsUTC = true;
 
     DateInstance* thisDateObj = asDateInstance(thisValue); 
-    double milli = thisDateObj->internalNumber();
-    if (isnan(milli))
-        return jsNontrivialString(exec, "Invalid Date");
 
     GregorianDateTime t;
-    thisDateObj->msToGregorianDateTime(milli, utc, t);
-    return jsNontrivialString(exec, formatDateUTCVariant(t) + " " + formatTime(t, utc));
+    if (!thisDateObj->getGregorianDateTime(exec, outputIsUTC, t))
+        return jsNontrivialString(exec, "Invalid Date");
+    return jsNontrivialString(exec, formatDateUTCVariant(t) + " " + formatTime(t, outputIsUTC));
 }
 
 JSValue JSC_HOST_CALL dateProtoFuncGetMonth(ExecState* exec, JSObject*, JSValue thisValue, const ArgList&)
@@ -613,15 +580,13 @@ JSValue JSC_HOST_CALL dateProtoFuncGetMonth(ExecState* exec, JSObject*, JSValue
     if (!thisValue.inherits(&DateInstance::info))
         return throwError(exec, TypeError);
 
-    const bool utc = false;
+    const bool outputIsUTC = false;
 
     DateInstance* thisDateObj = asDateInstance(thisValue); 
-    double milli = thisDateObj->internalNumber();
-    if (isnan(milli))
-        return jsNaN(exec);
 
     GregorianDateTime t;
-    thisDateObj->msToGregorianDateTime(milli, utc, t);
+    if (!thisDateObj->getGregorianDateTime(exec, outputIsUTC, t))
+        return jsNaN(exec);
     return jsNumber(exec, t.month);
 }
 
@@ -630,15 +595,13 @@ JSValue JSC_HOST_CALL dateProtoFuncGetUTCMonth(ExecState* exec, JSObject*, JSVal
     if (!thisValue.inherits(&DateInstance::info))
         return throwError(exec, TypeError);
 
-    const bool utc = true;
+    const bool outputIsUTC = true;
 
     DateInstance* thisDateObj = asDateInstance(thisValue); 
-    double milli = thisDateObj->internalNumber();
-    if (isnan(milli))
-        return jsNaN(exec);
 
     GregorianDateTime t;
-    thisDateObj->msToGregorianDateTime(milli, utc, t);
+    if (!thisDateObj->getGregorianDateTime(exec, outputIsUTC, t))
+        return jsNaN(exec);
     return jsNumber(exec, t.month);
 }
 
@@ -647,15 +610,13 @@ JSValue JSC_HOST_CALL dateProtoFuncGetDate(ExecState* exec, JSObject*, JSValue t
     if (!thisValue.inherits(&DateInstance::info))
         return throwError(exec, TypeError);
 
-    const bool utc = false;
+    const bool outputIsUTC = false;
 
     DateInstance* thisDateObj = asDateInstance(thisValue); 
-    double milli = thisDateObj->internalNumber();
-    if (isnan(milli))
-        return jsNaN(exec);
 
     GregorianDateTime t;
-    thisDateObj->msToGregorianDateTime(milli, utc, t);
+    if (!thisDateObj->getGregorianDateTime(exec, outputIsUTC, t))
+        return jsNaN(exec);
     return jsNumber(exec, t.monthDay);
 }
 
@@ -664,15 +625,13 @@ JSValue JSC_HOST_CALL dateProtoFuncGetUTCDate(ExecState* exec, JSObject*, JSValu
     if (!thisValue.inherits(&DateInstance::info))
         return throwError(exec, TypeError);
 
-    const bool utc = true;
+    const bool outputIsUTC = true;
 
     DateInstance* thisDateObj = asDateInstance(thisValue); 
-    double milli = thisDateObj->internalNumber();
-    if (isnan(milli))
-        return jsNaN(exec);
 
     GregorianDateTime t;
-    thisDateObj->msToGregorianDateTime(milli, utc, t);
+    if (!thisDateObj->getGregorianDateTime(exec, outputIsUTC, t))
+        return jsNaN(exec);
     return jsNumber(exec, t.monthDay);
 }
 
@@ -681,15 +640,13 @@ JSValue JSC_HOST_CALL dateProtoFuncGetDay(ExecState* exec, JSObject*, JSValue th
     if (!thisValue.inherits(&DateInstance::info))
         return throwError(exec, TypeError);
 
-    const bool utc = false;
+    const bool outputIsUTC = false;
 
     DateInstance* thisDateObj = asDateInstance(thisValue); 
-    double milli = thisDateObj->internalNumber();
-    if (isnan(milli))
-        return jsNaN(exec);
 
     GregorianDateTime t;
-    thisDateObj->msToGregorianDateTime(milli, utc, t);
+    if (!thisDateObj->getGregorianDateTime(exec, outputIsUTC, t))
+        return jsNaN(exec);
     return jsNumber(exec, t.weekDay);
 }
 
@@ -698,15 +655,13 @@ JSValue JSC_HOST_CALL dateProtoFuncGetUTCDay(ExecState* exec, JSObject*, JSValue
     if (!thisValue.inherits(&DateInstance::info))
         return throwError(exec, TypeError);
 
-    const bool utc = true;
+    const bool outputIsUTC = true;
 
     DateInstance* thisDateObj = asDateInstance(thisValue); 
-    double milli = thisDateObj->internalNumber();
-    if (isnan(milli))
-        return jsNaN(exec);
 
     GregorianDateTime t;
-    thisDateObj->msToGregorianDateTime(milli, utc, t);
+    if (!thisDateObj->getGregorianDateTime(exec, outputIsUTC, t))
+        return jsNaN(exec);
     return jsNumber(exec, t.weekDay);
 }
 
@@ -715,15 +670,13 @@ JSValue JSC_HOST_CALL dateProtoFuncGetHours(ExecState* exec, JSObject*, JSValue
     if (!thisValue.inherits(&DateInstance::info))
         return throwError(exec, TypeError);
 
-    const bool utc = false;
+    const bool outputIsUTC = false;
 
     DateInstance* thisDateObj = asDateInstance(thisValue); 
-    double milli = thisDateObj->internalNumber();
-    if (isnan(milli))
-        return jsNaN(exec);
 
     GregorianDateTime t;
-    thisDateObj->msToGregorianDateTime(milli, utc, t);
+    if (!thisDateObj->getGregorianDateTime(exec, outputIsUTC, t))
+        return jsNaN(exec);
     return jsNumber(exec, t.hour);
 }
 
@@ -732,15 +685,13 @@ JSValue JSC_HOST_CALL dateProtoFuncGetUTCHours(ExecState* exec, JSObject*, JSVal
     if (!thisValue.inherits(&DateInstance::info))
         return throwError(exec, TypeError);
 
-    const bool utc = true;
+    const bool outputIsUTC = true;
 
     DateInstance* thisDateObj = asDateInstance(thisValue); 
-    double milli = thisDateObj->internalNumber();
-    if (isnan(milli))
-        return jsNaN(exec);
 
     GregorianDateTime t;
-    thisDateObj->msToGregorianDateTime(milli, utc, t);
+    if (!thisDateObj->getGregorianDateTime(exec, outputIsUTC, t))
+        return jsNaN(exec);
     return jsNumber(exec, t.hour);
 }
 
@@ -749,15 +700,13 @@ JSValue JSC_HOST_CALL dateProtoFuncGetMinutes(ExecState* exec, JSObject*, JSValu
     if (!thisValue.inherits(&DateInstance::info))
         return throwError(exec, TypeError);
 
-    const bool utc = false;
+    const bool outputIsUTC = false;
 
     DateInstance* thisDateObj = asDateInstance(thisValue); 
-    double milli = thisDateObj->internalNumber();
-    if (isnan(milli))
-        return jsNaN(exec);
 
     GregorianDateTime t;
-    thisDateObj->msToGregorianDateTime(milli, utc, t);
+    if (!thisDateObj->getGregorianDateTime(exec, outputIsUTC, t))
+        return jsNaN(exec);
     return jsNumber(exec, t.minute);
 }
 
@@ -766,15 +715,13 @@ JSValue JSC_HOST_CALL dateProtoFuncGetUTCMinutes(ExecState* exec, JSObject*, JSV
     if (!thisValue.inherits(&DateInstance::info))
         return throwError(exec, TypeError);
 
-    const bool utc = true;
+    const bool outputIsUTC = true;
 
     DateInstance* thisDateObj = asDateInstance(thisValue); 
-    double milli = thisDateObj->internalNumber();
-    if (isnan(milli))
-        return jsNaN(exec);
 
     GregorianDateTime t;
-    thisDateObj->msToGregorianDateTime(milli, utc, t);
+    if (!thisDateObj->getGregorianDateTime(exec, outputIsUTC, t))
+        return jsNaN(exec);
     return jsNumber(exec, t.minute);
 }
 
@@ -783,15 +730,13 @@ JSValue JSC_HOST_CALL dateProtoFuncGetSeconds(ExecState* exec, JSObject*, JSValu
     if (!thisValue.inherits(&DateInstance::info))
         return throwError(exec, TypeError);
 
-    const bool utc = false;
+    const bool outputIsUTC = false;
 
     DateInstance* thisDateObj = asDateInstance(thisValue); 
-    double milli = thisDateObj->internalNumber();
-    if (isnan(milli))
-        return jsNaN(exec);
 
     GregorianDateTime t;
-    thisDateObj->msToGregorianDateTime(milli, utc, t);
+    if (!thisDateObj->getGregorianDateTime(exec, outputIsUTC, t))
+        return jsNaN(exec);
     return jsNumber(exec, t.second);
 }
 
@@ -800,15 +745,13 @@ JSValue JSC_HOST_CALL dateProtoFuncGetUTCSeconds(ExecState* exec, JSObject*, JSV
     if (!thisValue.inherits(&DateInstance::info))
         return throwError(exec, TypeError);
 
-    const bool utc = true;
+    const bool outputIsUTC = true;
 
     DateInstance* thisDateObj = asDateInstance(thisValue); 
-    double milli = thisDateObj->internalNumber();
-    if (isnan(milli))
-        return jsNaN(exec);
 
     GregorianDateTime t;
-    thisDateObj->msToGregorianDateTime(milli, utc, t);
+    if (!thisDateObj->getGregorianDateTime(exec, outputIsUTC, t))
+        return jsNaN(exec);
     return jsNumber(exec, t.second);
 }
 
@@ -847,15 +790,13 @@ JSValue JSC_HOST_CALL dateProtoFuncGetTimezoneOffset(ExecState* exec, JSObject*,
     if (!thisValue.inherits(&DateInstance::info))
         return throwError(exec, TypeError);
 
-    const bool utc = false;
+    const bool outputIsUTC = false;
 
     DateInstance* thisDateObj = asDateInstance(thisValue); 
-    double milli = thisDateObj->internalNumber();
-    if (isnan(milli))
-        return jsNaN(exec);
 
     GregorianDateTime t;
-    thisDateObj->msToGregorianDateTime(milli, utc, t);
+    if (!thisDateObj->getGregorianDateTime(exec, outputIsUTC, t))
+        return jsNaN(exec);
     return jsNumber(exec, -gmtoffset(t) / minutesPerHour);
 }
 
@@ -890,7 +831,7 @@ static JSValue setNewValueFromTimeArgs(ExecState* exec, JSValue thisValue, const
     double ms = milli - secs * msPerSecond;
 
     GregorianDateTime t;
-    thisDateObj->msToGregorianDateTime(milli, inputIsUTC, t);
+    thisDateObj->getGregorianDateTime(exec, inputIsUTC, t);
 
     if (!fillStructuresUsingTimeArgs(exec, args, numArgsToUse, &ms, &t)) {
         JSValue result = jsNaN(exec);
@@ -922,11 +863,11 @@ static JSValue setNewValueFromDateArgs(ExecState* exec, JSValue thisValue, const
     if (numArgsToUse == 3 && isnan(milli))
         // Based on ECMA 262 15.9.5.40 - .41 (set[UTC]FullYear)
         // the time must be reset to +0 if it is NaN. 
-        thisDateObj->msToGregorianDateTime(0, true, t);
+        WTF::msToGregorianDateTime(0, true, t);
     else {
         double secs = floor(milli / msPerSecond);
         ms = milli - secs * msPerSecond;
-        thisDateObj->msToGregorianDateTime(milli, inputIsUTC, t);
+        thisDateObj->getGregorianDateTime(exec, inputIsUTC, t);
     }
     
     if (!fillStructuresUsingDateArgs(exec, args, numArgsToUse, &ms, &t)) {
@@ -1029,7 +970,7 @@ JSValue JSC_HOST_CALL dateProtoFuncSetYear(ExecState* exec, JSObject*, JSValue t
     if (!thisValue.inherits(&DateInstance::info))
         return throwError(exec, TypeError);
 
-    const bool utc = false;
+    const bool outputIsUTC = false;
 
     DateInstance* thisDateObj = asDateInstance(thisValue);     
     if (args.isEmpty()) { 
@@ -1045,11 +986,11 @@ JSValue JSC_HOST_CALL dateProtoFuncSetYear(ExecState* exec, JSObject*, JSValue t
     if (isnan(milli))
         // Based on ECMA 262 B.2.5 (setYear)
         // the time must be reset to +0 if it is NaN. 
-        thisDateObj->msToGregorianDateTime(0, true, t);
+        WTF::msToGregorianDateTime(0, true, t);
     else {   
         double secs = floor(milli / msPerSecond);
         ms = milli - secs * msPerSecond;
-        thisDateObj->msToGregorianDateTime(milli, utc, t);
+        thisDateObj->getGregorianDateTime(exec, outputIsUTC, t);
     }
     
     bool ok = true;
@@ -1061,7 +1002,7 @@ JSValue JSC_HOST_CALL dateProtoFuncSetYear(ExecState* exec, JSObject*, JSValue t
     }
             
     t.year = (year > 99 || year < 0) ? year - 1900 : year;
-    JSValue result = jsNumber(exec, gregorianDateTimeToMS(t, ms, utc));
+    JSValue result = jsNumber(exec, gregorianDateTimeToMS(t, ms, outputIsUTC));
     thisDateObj->setInternalValue(result);
     return result;
 }
@@ -1071,15 +1012,13 @@ JSValue JSC_HOST_CALL dateProtoFuncGetYear(ExecState* exec, JSObject*, JSValue t
     if (!thisValue.inherits(&DateInstance::info))
         return throwError(exec, TypeError);
 
-    const bool utc = false;
+    const bool outputIsUTC = false;
 
     DateInstance* thisDateObj = asDateInstance(thisValue); 
-    double milli = thisDateObj->internalNumber();
-    if (isnan(milli))
-        return jsNaN(exec);
 
     GregorianDateTime t;
-    thisDateObj->msToGregorianDateTime(milli, utc, t);
+    if (!thisDateObj->getGregorianDateTime(exec, outputIsUTC, t))
+        return jsNaN(exec);
 
     // NOTE: IE returns the full year even in getYear.
     return jsNumber(exec, t.year);
diff --git a/JavaScriptCore/runtime/DatePrototype.h b/JavaScriptCore/runtime/DatePrototype.h
index caed2d4..f565775 100644
--- a/JavaScriptCore/runtime/DatePrototype.h
+++ b/JavaScriptCore/runtime/DatePrototype.h
@@ -39,8 +39,12 @@ namespace JSC {
 
         static PassRefPtr<Structure> createStructure(JSValue prototype)
         {
-            return Structure::create(prototype, TypeInfo(ObjectType, HasDefaultGetPropertyNames));
+            return Structure::create(prototype, TypeInfo(ObjectType, StructureFlags));
         }
+
+    protected:
+        static const unsigned StructureFlags = OverridesGetOwnPropertySlot | DateInstance::StructureFlags;
+
     };
 
 } // namespace JSC
diff --git a/JavaScriptCore/runtime/FunctionPrototype.h b/JavaScriptCore/runtime/FunctionPrototype.h
index 0e38549..d1d6a1d 100644
--- a/JavaScriptCore/runtime/FunctionPrototype.h
+++ b/JavaScriptCore/runtime/FunctionPrototype.h
@@ -34,7 +34,7 @@ namespace JSC {
 
         static PassRefPtr<Structure> createStructure(JSValue proto)
         {
-            return Structure::create(proto, TypeInfo(ObjectType, HasStandardGetOwnPropertySlot | HasDefaultMark | HasDefaultGetPropertyNames));
+            return Structure::create(proto, TypeInfo(ObjectType, StructureFlags));
         }
 
     private:
diff --git a/JavaScriptCore/runtime/GetterSetter.h b/JavaScriptCore/runtime/GetterSetter.h
index 73dd854..68e9ea3 100644
--- a/JavaScriptCore/runtime/GetterSetter.h
+++ b/JavaScriptCore/runtime/GetterSetter.h
@@ -50,7 +50,7 @@ namespace JSC {
         void setSetter(JSObject* setter) { m_setter = setter; }
         static PassRefPtr<Structure> createStructure(JSValue prototype)
         {
-            return Structure::create(prototype, TypeInfo(GetterSetterType));
+            return Structure::create(prototype, TypeInfo(GetterSetterType, OverridesMarkChildren));
         }
     private:
         virtual bool isGetterSetter() const;
diff --git a/JavaScriptCore/runtime/GlobalEvalFunction.h b/JavaScriptCore/runtime/GlobalEvalFunction.h
index b62ad3e..389b1c3 100644
--- a/JavaScriptCore/runtime/GlobalEvalFunction.h
+++ b/JavaScriptCore/runtime/GlobalEvalFunction.h
@@ -37,9 +37,12 @@ namespace JSC {
 
         static PassRefPtr<Structure> createStructure(JSValue prototype) 
         { 
-            return Structure::create(prototype, TypeInfo(ObjectType, ImplementsHasInstance | HasStandardGetOwnPropertySlot));
+            return Structure::create(prototype, TypeInfo(ObjectType, StructureFlags));
         }
 
+    protected:
+        static const unsigned StructureFlags = ImplementsHasInstance | OverridesMarkChildren | OverridesGetPropertyNames | PrototypeFunction::StructureFlags;
+
     private:
         virtual void markChildren(MarkStack&);
 
diff --git a/JavaScriptCore/runtime/InternalFunction.h b/JavaScriptCore/runtime/InternalFunction.h
index fdd5cc1..de9a1d6 100644
--- a/JavaScriptCore/runtime/InternalFunction.h
+++ b/JavaScriptCore/runtime/InternalFunction.h
@@ -42,10 +42,12 @@ namespace JSC {
 
         static PassRefPtr<Structure> createStructure(JSValue proto) 
         { 
-            return Structure::create(proto, TypeInfo(ObjectType, ImplementsHasInstance | HasStandardGetOwnPropertySlot | HasDefaultMark)); 
+            return Structure::create(proto, TypeInfo(ObjectType, StructureFlags)); 
         }
 
     protected:
+        static const unsigned StructureFlags = ImplementsHasInstance | JSObject::StructureFlags;
+
         InternalFunction(NonNullPassRefPtr<Structure> structure) : JSObject(structure) { }
         InternalFunction(JSGlobalData*, NonNullPassRefPtr<Structure>, const Identifier&);
 
diff --git a/JavaScriptCore/runtime/JSAPIValueWrapper.h b/JavaScriptCore/runtime/JSAPIValueWrapper.h
index 88a8493..aca550e 100644
--- a/JavaScriptCore/runtime/JSAPIValueWrapper.h
+++ b/JavaScriptCore/runtime/JSAPIValueWrapper.h
@@ -39,7 +39,7 @@ namespace JSC {
 
         static PassRefPtr<Structure> createStructure(JSValue prototype)
         {
-            return Structure::create(prototype, TypeInfo(CompoundType));
+            return Structure::create(prototype, TypeInfo(CompoundType, OverridesMarkChildren | OverridesGetPropertyNames));
         }
 
         
diff --git a/JavaScriptCore/runtime/JSActivation.h b/JavaScriptCore/runtime/JSActivation.h
index 583b988..ee98191 100644
--- a/JavaScriptCore/runtime/JSActivation.h
+++ b/JavaScriptCore/runtime/JSActivation.h
@@ -66,7 +66,10 @@ namespace JSC {
         virtual const ClassInfo* classInfo() const { return &info; }
         static const ClassInfo info;
 
-        static PassRefPtr<Structure> createStructure(JSValue proto) { return Structure::create(proto, TypeInfo(ObjectType, NeedsThisConversion)); }
+        static PassRefPtr<Structure> createStructure(JSValue proto) { return Structure::create(proto, TypeInfo(ObjectType, StructureFlags)); }
+
+    protected:
+        static const unsigned StructureFlags = OverridesGetOwnPropertySlot | NeedsThisConversion | OverridesMarkChildren | OverridesGetPropertyNames | JSVariableObject::StructureFlags;
 
     private:
         struct JSActivationData : public JSVariableObjectData {
diff --git a/JavaScriptCore/runtime/JSArray.h b/JavaScriptCore/runtime/JSArray.h
index 66b5a1d..8c22451 100644
--- a/JavaScriptCore/runtime/JSArray.h
+++ b/JavaScriptCore/runtime/JSArray.h
@@ -87,12 +87,13 @@ namespace JSC {
 
         static PassRefPtr<Structure> createStructure(JSValue prototype)
         {
-            return Structure::create(prototype, TypeInfo(ObjectType));
+            return Structure::create(prototype, TypeInfo(ObjectType, StructureFlags));
         }
         
         inline void markChildrenDirect(MarkStack& markStack);
 
     protected:
+        static const unsigned StructureFlags = OverridesGetOwnPropertySlot | OverridesMarkChildren | OverridesGetPropertyNames | JSObject::StructureFlags;
         virtual void put(ExecState*, const Identifier& propertyName, JSValue, PutPropertySlot&);
         virtual bool deleteProperty(ExecState*, const Identifier& propertyName);
         virtual bool deleteProperty(ExecState*, unsigned propertyName);
@@ -157,7 +158,7 @@ namespace JSC {
     inline void MarkStack::markChildren(JSCell* cell)
     {
         ASSERT(Heap::isCellMarked(cell));
-        if (cell->structure()->typeInfo().hasDefaultMark()) {
+        if (!cell->structure()->typeInfo().overridesMarkChildren()) {
 #ifdef NDEBUG
             asObject(cell)->markChildrenDirect(*this);
 #else
diff --git a/JavaScriptCore/runtime/JSByteArray.cpp b/JavaScriptCore/runtime/JSByteArray.cpp
index 90d39f0..5e5003b 100644
--- a/JavaScriptCore/runtime/JSByteArray.cpp
+++ b/JavaScriptCore/runtime/JSByteArray.cpp
@@ -45,7 +45,7 @@ JSByteArray::JSByteArray(ExecState* exec, NonNullPassRefPtr<Structure> structure
     
 PassRefPtr<Structure> JSByteArray::createStructure(JSValue prototype)
 {
-    PassRefPtr<Structure> result = Structure::create(prototype, TypeInfo(ObjectType, HasDefaultMark));
+    PassRefPtr<Structure> result = Structure::create(prototype, TypeInfo(ObjectType, StructureFlags));
     return result;
 }
 
diff --git a/JavaScriptCore/runtime/JSByteArray.h b/JavaScriptCore/runtime/JSByteArray.h
index 006f4a2..fe6e124 100644
--- a/JavaScriptCore/runtime/JSByteArray.h
+++ b/JavaScriptCore/runtime/JSByteArray.h
@@ -91,6 +91,9 @@ namespace JSC {
 
         WTF::ByteArray* storage() const { return m_storage.get(); }
 
+    protected:
+        static const unsigned StructureFlags = OverridesGetOwnPropertySlot | OverridesGetPropertyNames | JSObject::StructureFlags;
+
     private:
         enum VPtrStealingHackType { VPtrStealingHack };
         JSByteArray(VPtrStealingHackType) 
diff --git a/JavaScriptCore/runtime/JSCell.cpp b/JavaScriptCore/runtime/JSCell.cpp
index aa93252..fae056e 100644
--- a/JavaScriptCore/runtime/JSCell.cpp
+++ b/JavaScriptCore/runtime/JSCell.cpp
@@ -78,11 +78,7 @@ extern const double Inf = NaNInf.doubles.Inf_Double;
 
 void* JSCell::operator new(size_t size, ExecState* exec)
 {
-#ifdef JAVASCRIPTCORE_BUILDING_ALL_IN_ONE_FILE
-    return exec->heap()->inlineAllocate(size);
-#else
     return exec->heap()->allocate(size);
-#endif
 }
 
 bool JSCell::getUInt32(uint32_t&) const
diff --git a/JavaScriptCore/runtime/JSCell.h b/JavaScriptCore/runtime/JSCell.h
index 503c6c4..722ae33 100644
--- a/JavaScriptCore/runtime/JSCell.h
+++ b/JavaScriptCore/runtime/JSCell.h
@@ -59,6 +59,7 @@ namespace JSC {
         virtual bool isGetterSetter() const;
         bool inherits(const ClassInfo*) const;
         virtual bool isAPIValueWrapper() const { return false; }
+        virtual bool isPropertyNameIterator() const { return false; }
 
         Structure* structure() const;
 
@@ -112,14 +113,6 @@ namespace JSC {
         Structure* m_structure;
     };
 
-    // FIXME: We should deprecate this and just use JSValue::asCell() instead.
-    JSCell* asCell(JSValue);
-
-    inline JSCell* asCell(JSValue value)
-    {
-        return value.asCell();
-    }
-
     inline JSCell::JSCell(Structure* structure)
         : m_structure(structure)
     {
@@ -162,11 +155,7 @@ namespace JSC {
 
     inline void* JSCell::operator new(size_t size, JSGlobalData* globalData)
     {
-#ifdef JAVASCRIPTCORE_BUILDING_ALL_IN_ONE_FILE
-        return globalData->heap.inlineAllocate(size);
-#else
         return globalData->heap.allocate(size);
-#endif
     }
 
     // --- JSValue inlines ----------------------------
@@ -342,11 +331,6 @@ namespace JSC {
             append(value.asCell());
     }
 
-    inline void Structure::markAggregate(MarkStack& markStack)
-    {
-        markStack.append(m_prototype);
-    }
-
     inline Heap* Heap::heap(JSValue v)
     {
         if (!v.isCell())
diff --git a/JavaScriptCore/runtime/JSFunction.h b/JavaScriptCore/runtime/JSFunction.h
index a9ac63e..fcac9aa 100644
--- a/JavaScriptCore/runtime/JSFunction.h
+++ b/JavaScriptCore/runtime/JSFunction.h
@@ -61,17 +61,20 @@ namespace JSC {
 
         static PassRefPtr<Structure> createStructure(JSValue prototype) 
         { 
-            return Structure::create(prototype, TypeInfo(ObjectType, ImplementsHasInstance)); 
+            return Structure::create(prototype, TypeInfo(ObjectType, StructureFlags)); 
         }
 
         NativeFunction nativeFunction()
         {
-            return *reinterpret_cast<NativeFunction*>(m_data);
+            return *WTF::bitwise_cast<NativeFunction*>(m_data);
         }
 
         virtual ConstructType getConstructData(ConstructData&);
         virtual CallType getCallData(CallData&);
 
+    protected:
+        const static unsigned StructureFlags = OverridesGetOwnPropertySlot | ImplementsHasInstance | OverridesMarkChildren | OverridesGetPropertyNames | InternalFunction::StructureFlags;
+
     private:
         JSFunction(NonNullPassRefPtr<Structure>);
 
@@ -94,7 +97,7 @@ namespace JSC {
         ScopeChain& scopeChain()
         {
             ASSERT(!isHostFunctionNonInline());
-            return *reinterpret_cast<ScopeChain*>(m_data);
+            return *WTF::bitwise_cast<ScopeChain*>(m_data);
         }
         void clearScopeChain()
         {
@@ -109,11 +112,11 @@ namespace JSC {
         void setScopeChain(const ScopeChain& sc)
         {
             ASSERT(!isHostFunctionNonInline());
-            *reinterpret_cast<ScopeChain*>(m_data) = sc;
+            *WTF::bitwise_cast<ScopeChain*>(m_data) = sc;
         }
         void setNativeFunction(NativeFunction func)
         {
-            *reinterpret_cast<NativeFunction*>(m_data) = func;
+            *WTF::bitwise_cast<NativeFunction*>(m_data) = func;
         }
         unsigned char m_data[sizeof(void*)];
     };
diff --git a/JavaScriptCore/runtime/JSGlobalData.h b/JavaScriptCore/runtime/JSGlobalData.h
index 3ad90ad..d2aa2da 100644
--- a/JavaScriptCore/runtime/JSGlobalData.h
+++ b/JavaScriptCore/runtime/JSGlobalData.h
@@ -30,6 +30,7 @@
 #define JSGlobalData_h
 
 #include "Collector.h"
+#include "DateInstanceCache.h"
 #include "ExecutableAllocator.h"
 #include "JITStubs.h"
 #include "JSValue.h"
@@ -116,7 +117,8 @@ namespace JSC {
         const MarkedArgumentBuffer* emptyList; // Lists are supposed to be allocated on the stack to have their elements properly marked, which is not the case here - but this list has nothing to mark.
         SmallStrings smallStrings;
         NumericStrings numericStrings;
-
+        DateInstanceCache dateInstanceCache;
+        
 #if ENABLE(ASSEMBLER)
         ExecutableAllocator executableAllocator;
 #endif
diff --git a/JavaScriptCore/runtime/JSGlobalObject.cpp b/JavaScriptCore/runtime/JSGlobalObject.cpp
index 3bb281e..cf3f1d1 100644
--- a/JavaScriptCore/runtime/JSGlobalObject.cpp
+++ b/JavaScriptCore/runtime/JSGlobalObject.cpp
@@ -89,7 +89,7 @@ static inline void markIfNeeded(MarkStack& markStack, JSValue v)
 static inline void markIfNeeded(MarkStack& markStack, const RefPtr<Structure>& s)
 {
     if (s)
-        s->markAggregate(markStack);
+        markIfNeeded(markStack, s->storedPrototype());
 }
 
 JSGlobalObject::~JSGlobalObject()
@@ -394,6 +394,21 @@ void JSGlobalObject::markChildren(MarkStack& markStack)
     markIfNeeded(markStack, d()->methodCallDummy);
 
     markIfNeeded(markStack, d()->errorStructure);
+    markIfNeeded(markStack, d()->argumentsStructure);
+    markIfNeeded(markStack, d()->arrayStructure);
+    markIfNeeded(markStack, d()->booleanObjectStructure);
+    markIfNeeded(markStack, d()->callbackConstructorStructure);
+    markIfNeeded(markStack, d()->callbackFunctionStructure);
+    markIfNeeded(markStack, d()->callbackObjectStructure);
+    markIfNeeded(markStack, d()->dateStructure);
+    markIfNeeded(markStack, d()->emptyObjectStructure);
+    markIfNeeded(markStack, d()->errorStructure);
+    markIfNeeded(markStack, d()->functionStructure);
+    markIfNeeded(markStack, d()->numberObjectStructure);
+    markIfNeeded(markStack, d()->prototypeFunctionStructure);
+    markIfNeeded(markStack, d()->regExpMatchesArrayStructure);
+    markIfNeeded(markStack, d()->regExpStructure);
+    markIfNeeded(markStack, d()->stringObjectStructure);
 
     // No need to mark the other structures, because their prototypes are all
     // guaranteed to be referenced elsewhere.
@@ -448,11 +463,7 @@ void JSGlobalObject::copyGlobalsTo(RegisterFile& registerFile)
 
 void* JSGlobalObject::operator new(size_t size, JSGlobalData* globalData)
 {
-#ifdef JAVASCRIPTCORE_BUILDING_ALL_IN_ONE_FILE
-    return globalData->heap.inlineAllocate(size);
-#else
     return globalData->heap.allocate(size);
-#endif
 }
 
 void JSGlobalObject::destroyJSGlobalObjectData(void* jsGlobalObjectData)
diff --git a/JavaScriptCore/runtime/JSGlobalObject.h b/JavaScriptCore/runtime/JSGlobalObject.h
index 2106783..720d3a5 100644
--- a/JavaScriptCore/runtime/JSGlobalObject.h
+++ b/JavaScriptCore/runtime/JSGlobalObject.h
@@ -267,10 +267,13 @@ namespace JSC {
 
         static PassRefPtr<Structure> createStructure(JSValue prototype)
         {
-            return Structure::create(prototype, TypeInfo(ObjectType));
+            return Structure::create(prototype, TypeInfo(ObjectType, StructureFlags));
         }
 
     protected:
+
+        static const unsigned StructureFlags = OverridesGetOwnPropertySlot | OverridesMarkChildren | OverridesGetPropertyNames | JSVariableObject::StructureFlags;
+
         struct GlobalPropertyInfo {
             GlobalPropertyInfo(const Identifier& i, JSValue v, unsigned a)
                 : identifier(i)
diff --git a/JavaScriptCore/runtime/JSNotAnObject.h b/JavaScriptCore/runtime/JSNotAnObject.h
index 0d9aca6..a271c4e 100644
--- a/JavaScriptCore/runtime/JSNotAnObject.h
+++ b/JavaScriptCore/runtime/JSNotAnObject.h
@@ -62,10 +62,13 @@ namespace JSC {
 
         static PassRefPtr<Structure> createStructure(JSValue prototype)
         {
-            return Structure::create(prototype, TypeInfo(ObjectType));
+            return Structure::create(prototype, TypeInfo(ObjectType, StructureFlags));
         }
 
      private:
+        
+        static const unsigned StructureFlags = OverridesGetOwnPropertySlot | OverridesMarkChildren | OverridesGetPropertyNames | JSObject::StructureFlags;
+
         // JSValue methods
         virtual JSValue toPrimitive(ExecState*, PreferredPrimitiveType) const;
         virtual bool getPrimitiveNumber(ExecState*, double& number, JSValue&);
diff --git a/JavaScriptCore/runtime/JSNumberCell.h b/JavaScriptCore/runtime/JSNumberCell.h
index 6a48081..309488f 100644
--- a/JavaScriptCore/runtime/JSNumberCell.h
+++ b/JavaScriptCore/runtime/JSNumberCell.h
@@ -68,23 +68,15 @@ namespace JSC {
 
         void* operator new(size_t size, ExecState* exec)
         {
-    #ifdef JAVASCRIPTCORE_BUILDING_ALL_IN_ONE_FILE
-            return exec->heap()->inlineAllocateNumber(size);
-    #else
             return exec->heap()->allocateNumber(size);
-    #endif
         }
 
         void* operator new(size_t size, JSGlobalData* globalData)
         {
-    #ifdef JAVASCRIPTCORE_BUILDING_ALL_IN_ONE_FILE
-            return globalData->heap.inlineAllocateNumber(size);
-    #else
             return globalData->heap.allocateNumber(size);
-    #endif
         }
 
-        static PassRefPtr<Structure> createStructure(JSValue proto) { return Structure::create(proto, TypeInfo(NumberType, NeedsThisConversion | HasDefaultMark)); }
+        static PassRefPtr<Structure> createStructure(JSValue proto) { return Structure::create(proto, TypeInfo(NumberType, OverridesGetOwnPropertySlot | NeedsThisConversion)); }
 
     private:
         JSNumberCell(JSGlobalData* globalData, double value)
diff --git a/JavaScriptCore/runtime/JSONObject.h b/JavaScriptCore/runtime/JSONObject.h
index 65c9803..ec3fa40 100644
--- a/JavaScriptCore/runtime/JSONObject.h
+++ b/JavaScriptCore/runtime/JSONObject.h
@@ -41,11 +41,14 @@ namespace JSC {
 
         static PassRefPtr<Structure> createStructure(JSValue prototype)
         {
-            return Structure::create(prototype, TypeInfo(ObjectType, HasDefaultMark | HasDefaultGetPropertyNames));
+            return Structure::create(prototype, TypeInfo(ObjectType, StructureFlags));
         }
 
         static void markStringifiers(MarkStack&, Stringifier*);
 
+    protected:
+        static const unsigned StructureFlags = OverridesGetOwnPropertySlot | JSObject::StructureFlags;
+
     private:
         virtual bool getOwnPropertySlot(ExecState*, const Identifier&, PropertySlot&);
         virtual bool getOwnPropertyDescriptor(ExecState*, const Identifier&, PropertyDescriptor&);
diff --git a/JavaScriptCore/runtime/JSObject.cpp b/JavaScriptCore/runtime/JSObject.cpp
index db2a9b2..6932ded 100644
--- a/JavaScriptCore/runtime/JSObject.cpp
+++ b/JavaScriptCore/runtime/JSObject.cpp
@@ -42,6 +42,25 @@ namespace JSC {
 
 ASSERT_CLASS_FITS_IN_CELL(JSObject);
 
+static inline void getEnumerablePropertyNames(ExecState* exec, const ClassInfo* classInfo, PropertyNameArray& propertyNames)
+{
+    // Add properties from the static hashtables of properties
+    for (; classInfo; classInfo = classInfo->parentClass) {
+        const HashTable* table = classInfo->propHashTable(exec);
+        if (!table)
+            continue;
+        table->initializeIfNeeded(exec);
+        ASSERT(table->table);
+
+        int hashSizeMask = table->compactSize - 1;
+        const HashEntry* entry = table->table;
+        for (int i = 0; i <= hashSizeMask; ++i, ++entry) {
+            if (entry->key() && !(entry->attributes() & DontEnum))
+                propertyNames.add(entry->key());
+        }
+    }
+}
+
 void JSObject::markChildren(MarkStack& markStack)
 {
 #ifndef NDEBUG
@@ -424,12 +443,29 @@ bool JSObject::getPropertySpecificValue(ExecState*, const Identifier& propertyNa
 
 void JSObject::getPropertyNames(ExecState* exec, PropertyNameArray& propertyNames)
 {
-    m_structure->getEnumerablePropertyNames(exec, propertyNames, this);
+    getOwnPropertyNames(exec, propertyNames);
+
+    if (prototype().isNull())
+        return;
+
+    JSObject* prototype = asObject(this->prototype());
+    while(1) {
+        if (prototype->structure()->typeInfo().overridesGetPropertyNames()) {
+            prototype->getPropertyNames(exec, propertyNames);
+            break;
+        }
+        prototype->getOwnPropertyNames(exec, propertyNames);
+        JSValue nextProto = prototype->prototype();
+        if (nextProto.isNull())
+            break;
+        prototype = asObject(nextProto);
+    }
 }
 
 void JSObject::getOwnPropertyNames(ExecState* exec, PropertyNameArray& propertyNames)
 {
-    m_structure->getOwnEnumerablePropertyNames(exec, propertyNames, this);
+    m_structure->getEnumerablePropertyNames(propertyNames);
+    getEnumerablePropertyNames(exec, classInfo(), propertyNames);
 }
 
 bool JSObject::toBoolean(ExecState*) const
diff --git a/JavaScriptCore/runtime/JSObject.h b/JavaScriptCore/runtime/JSObject.h
index 84b5f4b..5a89c40 100644
--- a/JavaScriptCore/runtime/JSObject.h
+++ b/JavaScriptCore/runtime/JSObject.h
@@ -202,15 +202,17 @@ namespace JSC {
         void allocatePropertyStorageInline(size_t oldSize, size_t newSize);
         bool isUsingInlineStorage() const { return m_structure->isUsingInlineStorage(); }
 
-        static const size_t inlineStorageCapacity = sizeof(EncodedJSValue) == 2 * sizeof(void*) ? 4 : 3;
-        static const size_t nonInlineBaseStorageCapacity = 16;
+        static const unsigned inlineStorageCapacity = sizeof(EncodedJSValue) == 2 * sizeof(void*) ? 4 : 3;
+        static const unsigned nonInlineBaseStorageCapacity = 16;
 
         static PassRefPtr<Structure> createStructure(JSValue prototype)
         {
-            return Structure::create(prototype, TypeInfo(ObjectType, HasStandardGetOwnPropertySlot | HasDefaultMark | HasDefaultGetPropertyNames));
+            return Structure::create(prototype, TypeInfo(ObjectType, StructureFlags));
         }
 
     protected:
+        static const unsigned StructureFlags = 0;
+
         void addAnonymousSlots(unsigned count);
         void putAnonymousValue(unsigned index, JSValue value)
         {
@@ -368,7 +370,7 @@ ALWAYS_INLINE bool JSObject::getOwnPropertySlot(ExecState* exec, const Identifie
 
 ALWAYS_INLINE bool JSCell::fastGetOwnPropertySlot(ExecState* exec, const Identifier& propertyName, PropertySlot& slot)
 {
-    if (structure()->typeInfo().hasStandardGetOwnPropertySlot())
+    if (!structure()->typeInfo().overridesGetOwnPropertySlot())
         return asObject(this)->inlineGetOwnPropertySlot(exec, propertyName, slot);
     return getOwnPropertySlot(exec, propertyName, slot);
 }
@@ -682,7 +684,7 @@ ALWAYS_INLINE void JSObject::markChildrenDirect(MarkStack& markStack)
 {
     JSCell::markChildren(markStack);
 
-    m_structure->markAggregate(markStack);
+    markStack.append(prototype());
     
     PropertyStorage storage = propertyStorage();
     size_t storageSize = m_structure->propertyStorageSize();
diff --git a/JavaScriptCore/runtime/JSPropertyNameIterator.cpp b/JavaScriptCore/runtime/JSPropertyNameIterator.cpp
index e08a3d9..6fd0344 100644
--- a/JavaScriptCore/runtime/JSPropertyNameIterator.cpp
+++ b/JavaScriptCore/runtime/JSPropertyNameIterator.cpp
@@ -29,26 +29,61 @@
 #include "config.h"
 #include "JSPropertyNameIterator.h"
 
+#include "JSGlobalObject.h"
+
 namespace JSC {
 
 ASSERT_CLASS_FITS_IN_CELL(JSPropertyNameIterator);
 
-JSPropertyNameIterator::~JSPropertyNameIterator()
+JSPropertyNameIterator* JSPropertyNameIterator::create(ExecState* exec, JSObject* o)
 {
+    ASSERT(!o->structure()->enumerationCache() ||
+            o->structure()->enumerationCache()->cachedStructure() != o->structure() ||
+            o->structure()->enumerationCache()->cachedPrototypeChain() != o->structure()->prototypeChain(exec));
+
+    PropertyNameArray propertyNames(exec);
+    o->getPropertyNames(exec, propertyNames);
+    size_t numCacheableSlots = 0;
+    if (!o->structure()->hasNonEnumerableProperties() && !o->structure()->hasAnonymousSlots() &&
+        !o->structure()->isUncacheableDictionary() && !o->structure()->typeInfo().overridesGetPropertyNames())
+        numCacheableSlots = o->structure()->propertyStorageSize();
+
+    JSPropertyNameIterator* jsPropertyNameIterator = new (exec) JSPropertyNameIterator(exec, propertyNames.data(), numCacheableSlots);
+
+    if (o->structure()->isDictionary())
+        return jsPropertyNameIterator;
+
+    if (o->structure()->typeInfo().overridesGetPropertyNames())
+        return jsPropertyNameIterator;
+    
+    size_t count = normalizePrototypeChain(exec, o);
+    StructureChain* structureChain = o->structure()->prototypeChain(exec);
+    RefPtr<Structure>* structure = structureChain->head();
+    for (size_t i = 0; i < count; ++i) {
+        if (structure[i]->typeInfo().overridesGetPropertyNames())
+            return jsPropertyNameIterator;
+    }
+
+    jsPropertyNameIterator->setCachedPrototypeChain(structureChain);
+    jsPropertyNameIterator->setCachedStructure(o->structure());
+    o->structure()->setEnumerationCache(jsPropertyNameIterator);
+    return jsPropertyNameIterator;
 }
 
-void JSPropertyNameIterator::markChildren(MarkStack& markStack)
+JSValue JSPropertyNameIterator::get(ExecState* exec, JSObject* base, size_t i)
 {
-    JSCell::markChildren(markStack);
-    if (m_object)
-        markStack.append(m_object);
+    JSValue& identifier = m_jsStrings[i];
+    if (m_cachedStructure == base->structure() && m_cachedPrototypeChain == base->structure()->prototypeChain(exec))
+        return identifier;
+
+    if (!base->hasProperty(exec, Identifier(exec, asString(identifier)->value())))
+        return JSValue();
+    return identifier;
 }
 
-void JSPropertyNameIterator::invalidate()
+void JSPropertyNameIterator::markChildren(MarkStack& markStack)
 {
-    ASSERT(m_position == m_end);
-    m_object = 0;
-    m_data.clear();
+    markStack.appendValues(m_jsStrings.get(), m_jsStringsSize, MayContainNullValues);
 }
 
 } // namespace JSC
diff --git a/JavaScriptCore/runtime/JSPropertyNameIterator.h b/JavaScriptCore/runtime/JSPropertyNameIterator.h
index d2849a8..529ae8b 100644
--- a/JavaScriptCore/runtime/JSPropertyNameIterator.h
+++ b/JavaScriptCore/runtime/JSPropertyNameIterator.h
@@ -31,6 +31,7 @@
 
 #include "JSObject.h"
 #include "JSString.h"
+#include "Operations.h"
 #include "PropertyNameArray.h"
 
 namespace JSC {
@@ -39,73 +40,63 @@ namespace JSC {
     class JSObject;
 
     class JSPropertyNameIterator : public JSCell {
+        friend class JIT;
+
     public:
-        static JSPropertyNameIterator* create(ExecState*, JSValue);
+        static JSPropertyNameIterator* create(ExecState*, JSObject*);
+        
+        static PassRefPtr<Structure> createStructure(JSValue prototype)
+        {
+            return Structure::create(prototype, TypeInfo(CompoundType, OverridesMarkChildren));
+        }
 
-        virtual ~JSPropertyNameIterator();
+        virtual bool isPropertyNameIterator() const { return true; }
 
         virtual void markChildren(MarkStack&);
 
-        JSValue next(ExecState*);
-        void invalidate();
-        
-        static PassRefPtr<Structure> createStructure(JSValue prototype)
+        bool getOffset(size_t i, int& offset)
         {
-            return Structure::create(prototype, TypeInfo(CompoundType));
+            if (i >= m_numCacheableSlots)
+                return false;
+            offset = i;
+            return true;
         }
+
+        JSValue get(ExecState*, JSObject*, size_t i);
+        size_t size() { return m_jsStringsSize; }
+
+        void setCachedStructure(Structure* structure) { m_cachedStructure = structure; }
+        Structure* cachedStructure() { return m_cachedStructure; }
+
+        void setCachedPrototypeChain(NonNullPassRefPtr<StructureChain> cachedPrototypeChain) { m_cachedPrototypeChain = cachedPrototypeChain; }
+        StructureChain* cachedPrototypeChain() { return m_cachedPrototypeChain.get(); }
+
     private:
-        JSPropertyNameIterator(ExecState*);
-        JSPropertyNameIterator(ExecState*, JSObject*, PassRefPtr<PropertyNameArrayData> propertyNameArrayData);
+        JSPropertyNameIterator(ExecState*, PropertyNameArrayData* propertyNameArrayData, size_t numCacheableSlot);
 
-        JSObject* m_object;
-        RefPtr<PropertyNameArrayData> m_data;
-        PropertyNameArrayData::const_iterator m_position;
-        PropertyNameArrayData::const_iterator m_end;
+        Structure* m_cachedStructure;
+        RefPtr<StructureChain> m_cachedPrototypeChain;
+        uint32_t m_numCacheableSlots;
+        uint32_t m_jsStringsSize;
+        OwnArrayPtr<JSValue> m_jsStrings;
     };
 
-inline JSPropertyNameIterator::JSPropertyNameIterator(ExecState* exec)
+inline JSPropertyNameIterator::JSPropertyNameIterator(ExecState* exec, PropertyNameArrayData* propertyNameArrayData, size_t numCacheableSlots)
     : JSCell(exec->globalData().propertyNameIteratorStructure.get())
-    , m_object(0)
-    , m_position(0)
-    , m_end(0)
+    , m_cachedStructure(0)
+    , m_numCacheableSlots(numCacheableSlots)
+    , m_jsStringsSize(propertyNameArrayData->propertyNameVector().size())
+    , m_jsStrings(new JSValue[m_jsStringsSize])
 {
+    PropertyNameArrayData::PropertyNameVector& propertyNameVector = propertyNameArrayData->propertyNameVector();
+    for (size_t i = 0; i < m_jsStringsSize; ++i)
+        m_jsStrings[i] = jsOwnedString(exec, propertyNameVector[i].ustring());
 }
 
-inline JSPropertyNameIterator::JSPropertyNameIterator(ExecState* exec, JSObject* object, PassRefPtr<PropertyNameArrayData> propertyNameArrayData)
-    : JSCell(exec->globalData().propertyNameIteratorStructure.get())
-    , m_object(object)
-    , m_data(propertyNameArrayData)
-    , m_position(m_data->begin())
-    , m_end(m_data->end())
-{
-}
-
-inline JSPropertyNameIterator* JSPropertyNameIterator::create(ExecState* exec, JSValue v)
+inline void Structure::setEnumerationCache(JSPropertyNameIterator* enumerationCache)
 {
-    if (v.isUndefinedOrNull())
-        return new (exec) JSPropertyNameIterator(exec);
-
-    JSObject* o = v.toObject(exec);
-    PropertyNameArray propertyNames(exec);
-    o->getPropertyNames(exec, propertyNames);
-    return new (exec) JSPropertyNameIterator(exec, o, propertyNames.releaseData());
-}
-
-inline JSValue JSPropertyNameIterator::next(ExecState* exec)
-{
-    if (m_position == m_end)
-        return JSValue();
-
-    if (m_data->cachedStructure() == m_object->structure() && m_data->cachedPrototypeChain() == m_object->structure()->prototypeChain(exec))
-        return jsOwnedString(exec, (*m_position++).ustring());
-
-    do {
-        if (m_object->hasProperty(exec, *m_position))
-            return jsOwnedString(exec, (*m_position++).ustring());
-        m_position++;
-    } while (m_position != m_end);
-
-    return JSValue();
+    ASSERT(!isDictionary());
+    m_enumerationCache = enumerationCache;
 }
 
 } // namespace JSC
diff --git a/JavaScriptCore/runtime/JSStaticScopeObject.h b/JavaScriptCore/runtime/JSStaticScopeObject.h
index 5eb0e4b..2542878 100644
--- a/JavaScriptCore/runtime/JSStaticScopeObject.h
+++ b/JavaScriptCore/runtime/JSStaticScopeObject.h
@@ -57,7 +57,10 @@ namespace JSC{
         virtual void put(ExecState*, const Identifier&, JSValue, PutPropertySlot&);
         void putWithAttributes(ExecState*, const Identifier&, JSValue, unsigned attributes);
 
-        static PassRefPtr<Structure> createStructure(JSValue proto) { return Structure::create(proto, TypeInfo(ObjectType, NeedsThisConversion)); }
+        static PassRefPtr<Structure> createStructure(JSValue proto) { return Structure::create(proto, TypeInfo(ObjectType, StructureFlags)); }
+
+    protected:
+        static const unsigned StructureFlags = OverridesGetOwnPropertySlot | NeedsThisConversion | OverridesMarkChildren | OverridesGetPropertyNames | JSVariableObject::StructureFlags;
 
     private:
         JSStaticScopeObjectData* d() { return static_cast<JSStaticScopeObjectData*>(JSVariableObject::d); }
diff --git a/JavaScriptCore/runtime/JSString.cpp b/JavaScriptCore/runtime/JSString.cpp
index 91ddaeb..20ba868 100644
--- a/JavaScriptCore/runtime/JSString.cpp
+++ b/JavaScriptCore/runtime/JSString.cpp
@@ -139,45 +139,4 @@ bool JSString::getOwnPropertySlot(ExecState* exec, unsigned propertyName, Proper
     return JSString::getOwnPropertySlot(exec, Identifier::from(exec, propertyName), slot);
 }
 
-JSString* jsString(JSGlobalData* globalData, const UString& s)
-{
-    int size = s.size();
-    if (!size)
-        return globalData->smallStrings.emptyString(globalData);
-    if (size == 1) {
-        UChar c = s.data()[0];
-        if (c <= 0xFF)
-            return globalData->smallStrings.singleCharacterString(globalData, c);
-    }
-    return new (globalData) JSString(globalData, s);
-}
-    
-JSString* jsSubstring(JSGlobalData* globalData, const UString& s, unsigned offset, unsigned length)
-{
-    ASSERT(offset <= static_cast<unsigned>(s.size()));
-    ASSERT(length <= static_cast<unsigned>(s.size()));
-    ASSERT(offset + length <= static_cast<unsigned>(s.size()));
-    if (!length)
-        return globalData->smallStrings.emptyString(globalData);
-    if (length == 1) {
-        UChar c = s.data()[offset];
-        if (c <= 0xFF)
-            return globalData->smallStrings.singleCharacterString(globalData, c);
-    }
-    return new (globalData) JSString(globalData, UString::Rep::create(s.rep(), offset, length));
-}
-
-JSString* jsOwnedString(JSGlobalData* globalData, const UString& s)
-{
-    int size = s.size();
-    if (!size)
-        return globalData->smallStrings.emptyString(globalData);
-    if (size == 1) {
-        UChar c = s.data()[0];
-        if (c <= 0xFF)
-            return globalData->smallStrings.singleCharacterString(globalData, c);
-    }
-    return new (globalData) JSString(globalData, s, JSString::HasOtherOwner);
-}
-
 } // namespace JSC
diff --git a/JavaScriptCore/runtime/JSString.h b/JavaScriptCore/runtime/JSString.h
index 1e46551..39dfe75 100644
--- a/JavaScriptCore/runtime/JSString.h
+++ b/JavaScriptCore/runtime/JSString.h
@@ -92,7 +92,7 @@ namespace JSC {
         bool canGetIndex(unsigned i) { return i < static_cast<unsigned>(m_value.size()); }
         JSString* getIndex(JSGlobalData*, unsigned);
 
-        static PassRefPtr<Structure> createStructure(JSValue proto) { return Structure::create(proto, TypeInfo(StringType, NeedsThisConversion | HasDefaultMark)); }
+        static PassRefPtr<Structure> createStructure(JSValue proto) { return Structure::create(proto, TypeInfo(StringType, OverridesGetOwnPropertySlot | NeedsThisConversion)); }
 
     private:
         enum VPtrStealingHackType { VPtrStealingHack };
@@ -169,6 +169,47 @@ namespace JSC {
         return jsSingleCharacterSubstring(globalData, m_value, i);
     }
 
+    inline JSString* jsString(JSGlobalData* globalData, const UString& s)
+    {
+        int size = s.size();
+        if (!size)
+            return globalData->smallStrings.emptyString(globalData);
+        if (size == 1) {
+            UChar c = s.data()[0];
+            if (c <= 0xFF)
+                return globalData->smallStrings.singleCharacterString(globalData, c);
+        }
+        return new (globalData) JSString(globalData, s);
+    }
+        
+    inline JSString* jsSubstring(JSGlobalData* globalData, const UString& s, unsigned offset, unsigned length)
+    {
+        ASSERT(offset <= static_cast<unsigned>(s.size()));
+        ASSERT(length <= static_cast<unsigned>(s.size()));
+        ASSERT(offset + length <= static_cast<unsigned>(s.size()));
+        if (!length)
+            return globalData->smallStrings.emptyString(globalData);
+        if (length == 1) {
+            UChar c = s.data()[offset];
+            if (c <= 0xFF)
+                return globalData->smallStrings.singleCharacterString(globalData, c);
+        }
+        return new (globalData) JSString(globalData, UString::Rep::create(s.rep(), offset, length));
+    }
+
+    inline JSString* jsOwnedString(JSGlobalData* globalData, const UString& s)
+    {
+        int size = s.size();
+        if (!size)
+            return globalData->smallStrings.emptyString(globalData);
+        if (size == 1) {
+            UChar c = s.data()[0];
+            if (c <= 0xFF)
+                return globalData->smallStrings.singleCharacterString(globalData, c);
+        }
+        return new (globalData) JSString(globalData, s, JSString::HasOtherOwner);
+    }
+
     inline JSString* jsEmptyString(ExecState* exec) { return jsEmptyString(&exec->globalData()); }
     inline JSString* jsString(ExecState* exec, const UString& s) { return jsString(&exec->globalData(), s); }
     inline JSString* jsSingleCharacterString(ExecState* exec, UChar c) { return jsSingleCharacterString(&exec->globalData(), c); }
diff --git a/JavaScriptCore/runtime/JSTypeInfo.h b/JavaScriptCore/runtime/JSTypeInfo.h
index 279510b..7c89600 100644
--- a/JavaScriptCore/runtime/JSTypeInfo.h
+++ b/JavaScriptCore/runtime/JSTypeInfo.h
@@ -40,9 +40,9 @@ namespace JSC {
     static const unsigned OverridesHasInstance = 1 << 2;
     static const unsigned ImplementsDefaultHasInstance = 1 << 3;
     static const unsigned NeedsThisConversion = 1 << 4;
-    static const unsigned HasStandardGetOwnPropertySlot = 1 << 5;
-    static const unsigned HasDefaultMark = 1 << 6;
-    static const unsigned HasDefaultGetPropertyNames = 1 << 7;
+    static const unsigned OverridesGetOwnPropertySlot = 1 << 5;
+    static const unsigned OverridesMarkChildren = 1 << 6;
+    static const unsigned OverridesGetPropertyNames = 1 << 7;
 
     class TypeInfo {
         friend class JIT;
@@ -63,9 +63,9 @@ namespace JSC {
         bool implementsHasInstance() const { return m_flags & ImplementsHasInstance; }
         bool overridesHasInstance() const { return m_flags & OverridesHasInstance; }
         bool needsThisConversion() const { return m_flags & NeedsThisConversion; }
-        bool hasStandardGetOwnPropertySlot() const { return m_flags & HasStandardGetOwnPropertySlot; }
-        bool hasDefaultMark() const { return m_flags & HasDefaultMark; }
-        bool hasDefaultGetPropertyNames() const { return m_flags & HasDefaultGetPropertyNames; }
+        bool overridesGetOwnPropertySlot() const { return m_flags & OverridesGetOwnPropertySlot; }
+        bool overridesMarkChildren() const { return m_flags & OverridesMarkChildren; }
+        bool overridesGetPropertyNames() const { return m_flags & OverridesGetPropertyNames; }
         unsigned flags() const { return m_flags; }
 
     private:
diff --git a/JavaScriptCore/runtime/JSValue.h b/JavaScriptCore/runtime/JSValue.h
index 3c511d8..1063cdc 100644
--- a/JavaScriptCore/runtime/JSValue.h
+++ b/JavaScriptCore/runtime/JSValue.h
@@ -373,6 +373,14 @@ namespace JSC {
         return static_cast<uint32_t>(val);
     }
 
+    // FIXME: We should deprecate this and just use JSValue::asCell() instead.
+    JSCell* asCell(JSValue);
+
+    inline JSCell* asCell(JSValue value)
+    {
+        return value.asCell();
+    }
+
     ALWAYS_INLINE int32_t JSValue::toInt32(ExecState* exec) const
     {
         if (isInt32())
diff --git a/JavaScriptCore/runtime/JSVariableObject.h b/JavaScriptCore/runtime/JSVariableObject.h
index 66e78c3..d8b1479 100644
--- a/JavaScriptCore/runtime/JSVariableObject.h
+++ b/JavaScriptCore/runtime/JSVariableObject.h
@@ -60,10 +60,11 @@ namespace JSC {
 
         static PassRefPtr<Structure> createStructure(JSValue prototype)
         {
-            return Structure::create(prototype, TypeInfo(ObjectType, HasStandardGetOwnPropertySlot | HasDefaultMark));
+            return Structure::create(prototype, TypeInfo(ObjectType, StructureFlags));
         }
         
     protected:
+        static const unsigned StructureFlags = OverridesGetPropertyNames | JSObject::StructureFlags;
         // Subclasses of JSVariableObject can subclass this struct to add data
         // without increasing their own size (since there's a hard limit on the
         // size of a JSCell).
diff --git a/JavaScriptCore/runtime/JSWrapperObject.h b/JavaScriptCore/runtime/JSWrapperObject.h
index 723b75d..191ff3b 100644
--- a/JavaScriptCore/runtime/JSWrapperObject.h
+++ b/JavaScriptCore/runtime/JSWrapperObject.h
@@ -38,7 +38,7 @@ namespace JSC {
 
         static PassRefPtr<Structure> createStructure(JSValue prototype) 
         { 
-            return Structure::create(prototype, TypeInfo(ObjectType, HasStandardGetOwnPropertySlot | HasDefaultGetPropertyNames | HasDefaultMark));
+            return Structure::create(prototype, TypeInfo(ObjectType, StructureFlags));
         }
 
     private:
diff --git a/JavaScriptCore/runtime/MarkStack.h b/JavaScriptCore/runtime/MarkStack.h
index ba00057..ea09f54 100644
--- a/JavaScriptCore/runtime/MarkStack.h
+++ b/JavaScriptCore/runtime/MarkStack.h
@@ -47,7 +47,7 @@ namespace JSC {
         }
 
         ALWAYS_INLINE void append(JSValue);
-        ALWAYS_INLINE void append(JSCell*);
+        void append(JSCell*);
         
         ALWAYS_INLINE void appendValues(Register* values, size_t count, MarkSetProperties properties = NoNullValues)
         {
diff --git a/JavaScriptCore/runtime/MathObject.h b/JavaScriptCore/runtime/MathObject.h
index fee5ec5..7f474b8 100644
--- a/JavaScriptCore/runtime/MathObject.h
+++ b/JavaScriptCore/runtime/MathObject.h
@@ -37,8 +37,11 @@ namespace JSC {
 
         static PassRefPtr<Structure> createStructure(JSValue prototype)
         {
-            return Structure::create(prototype, TypeInfo(ObjectType, HasDefaultMark | HasDefaultGetPropertyNames));
+            return Structure::create(prototype, TypeInfo(ObjectType, StructureFlags));
         }
+
+    protected:
+        static const unsigned StructureFlags = OverridesGetOwnPropertySlot | JSObject::StructureFlags;
     };
 
 } // namespace JSC
diff --git a/JavaScriptCore/runtime/NumberConstructor.h b/JavaScriptCore/runtime/NumberConstructor.h
index 908c55f..cf19b6f 100644
--- a/JavaScriptCore/runtime/NumberConstructor.h
+++ b/JavaScriptCore/runtime/NumberConstructor.h
@@ -39,11 +39,14 @@ namespace JSC {
 
         static PassRefPtr<Structure> createStructure(JSValue proto) 
         { 
-            return Structure::create(proto, TypeInfo(ObjectType, ImplementsHasInstance | HasDefaultMark | HasDefaultGetPropertyNames)); 
+            return Structure::create(proto, TypeInfo(ObjectType, StructureFlags)); 
         }
 
         enum { NaNValue, NegInfinity, PosInfinity, MaxValue, MinValue };
 
+    protected:
+        static const unsigned StructureFlags = OverridesGetOwnPropertySlot | ImplementsHasInstance | InternalFunction::StructureFlags;
+
     private:
         virtual ConstructType getConstructData(ConstructData&);
         virtual CallType getCallData(CallData&);
diff --git a/JavaScriptCore/runtime/NumberObject.h b/JavaScriptCore/runtime/NumberObject.h
index ca3923d..8223a90 100644
--- a/JavaScriptCore/runtime/NumberObject.h
+++ b/JavaScriptCore/runtime/NumberObject.h
@@ -30,17 +30,19 @@ namespace JSC {
         explicit NumberObject(NonNullPassRefPtr<Structure>);
 
         static const ClassInfo info;
-#if USE(JSVALUE32)
+
         static PassRefPtr<Structure> createStructure(JSValue prototype)
         {
-            return Structure::create(prototype, TypeInfo(ObjectType, HasStandardGetOwnPropertySlot | HasDefaultGetPropertyNames));
+            return Structure::create(prototype, TypeInfo(ObjectType, StructureFlags));
         }
+
+    protected:
+#if USE(JSVALUE32)
+        static const unsigned StructureFlags = OverridesMarkChildren | JSWrapperObject::StructureFlags;
 #else
-        static PassRefPtr<Structure> createStructure(JSValue prototype)
-        {
-            return Structure::create(prototype, TypeInfo(ObjectType, HasStandardGetOwnPropertySlot | HasDefaultMark | HasDefaultGetPropertyNames));
-        }
+        static const unsigned StructureFlags = JSWrapperObject::StructureFlags;
 #endif
+
     private:
         virtual const ClassInfo* classInfo() const { return &info; }
 
diff --git a/JavaScriptCore/runtime/ObjectConstructor.cpp b/JavaScriptCore/runtime/ObjectConstructor.cpp
index a456423..837d5a6 100644
--- a/JavaScriptCore/runtime/ObjectConstructor.cpp
+++ b/JavaScriptCore/runtime/ObjectConstructor.cpp
@@ -125,6 +125,7 @@ JSValue JSC_HOST_CALL objectConstructorGetOwnPropertyDescriptor(ExecState* exec,
     return description;
 }
 
+// FIXME: Use the enumeration cache.
 JSValue JSC_HOST_CALL objectConstructorKeys(ExecState* exec, JSObject*, JSValue, const ArgList& args)
 {
     if (!args.at(0).isObject())
diff --git a/JavaScriptCore/runtime/Operations.h b/JavaScriptCore/runtime/Operations.h
index 5da9e38..1aa68b3 100644
--- a/JavaScriptCore/runtime/Operations.h
+++ b/JavaScriptCore/runtime/Operations.h
@@ -224,15 +224,15 @@ namespace JSC {
         return jsAddSlowCase(callFrame, v1, v2);
     }
 
-    inline size_t countPrototypeChainEntriesAndCheckForProxies(CallFrame* callFrame, JSValue baseValue, const PropertySlot& slot)
+    inline size_t normalizePrototypeChain(CallFrame* callFrame, JSValue base, JSValue slotBase)
     {
-        JSCell* cell = asCell(baseValue);
+        JSCell* cell = asCell(base);
         size_t count = 0;
 
-        while (slot.slotBase() != cell) {
+        while (slotBase != cell) {
             JSValue v = cell->structure()->prototypeForLookup(callFrame);
 
-            // If we didn't find slotBase in baseValue's prototype chain, then baseValue
+            // If we didn't find slotBase in base's prototype chain, then base
             // must be a proxy for another object.
 
             if (v.isNull())
@@ -252,6 +252,25 @@ namespace JSC {
         return count;
     }
 
+    inline size_t normalizePrototypeChain(CallFrame* callFrame, JSCell* base)
+    {
+        size_t count = 0;
+        while (1) {
+            JSValue v = base->structure()->prototypeForLookup(callFrame);
+            if (v.isNull())
+                return count;
+
+            base = asCell(v);
+
+            // Since we're accessing a prototype in a loop, it's a good bet that it
+            // should not be treated as a dictionary.
+            if (base->structure()->isDictionary())
+                asObject(base)->setStructure(Structure::fromDictionaryTransition(base->structure()));
+
+            ++count;
+        }
+    }
+
     ALWAYS_INLINE JSValue resolveBase(CallFrame* callFrame, Identifier& property, ScopeChainNode* scopeChain)
     {
         ScopeChainIterator iter = scopeChain->begin();
diff --git a/JavaScriptCore/runtime/PropertyNameArray.cpp b/JavaScriptCore/runtime/PropertyNameArray.cpp
index 0878e73..c28b6a4 100644
--- a/JavaScriptCore/runtime/PropertyNameArray.cpp
+++ b/JavaScriptCore/runtime/PropertyNameArray.cpp
@@ -21,6 +21,9 @@
 #include "config.h"
 #include "PropertyNameArray.h"
 
+#include "Structure.h"
+#include "StructureChain.h"
+
 namespace JSC {
 
 static const size_t setThreshold = 20;
@@ -44,7 +47,7 @@ void PropertyNameArray::add(UString::Rep* identifier)
             return;
     }
 
-    m_data->propertyNameVector().append(Identifier(m_globalData, identifier));
+    addKnownUnique(identifier);
 }
 
 } // namespace JSC
diff --git a/JavaScriptCore/runtime/PropertyNameArray.h b/JavaScriptCore/runtime/PropertyNameArray.h
index afcc83f..3dbcc9d 100644
--- a/JavaScriptCore/runtime/PropertyNameArray.h
+++ b/JavaScriptCore/runtime/PropertyNameArray.h
@@ -23,45 +23,35 @@
 
 #include "CallFrame.h"
 #include "Identifier.h"
-#include "Structure.h"
 #include <wtf/HashSet.h>
+#include <wtf/OwnArrayPtr.h>
 #include <wtf/Vector.h>
 
 namespace JSC {
+    
+    class Structure;
+    class StructureChain;
 
+    // FIXME: Rename to PropertyNameArray.
     class PropertyNameArrayData : public RefCounted<PropertyNameArrayData> {
     public:
         typedef Vector<Identifier, 20> PropertyNameVector;
-        typedef PropertyNameVector::const_iterator const_iterator;
 
         static PassRefPtr<PropertyNameArrayData> create() { return adoptRef(new PropertyNameArrayData); }
 
-        const_iterator begin() const { return m_propertyNameVector.begin(); }
-        const_iterator end() const { return m_propertyNameVector.end(); }
-
         PropertyNameVector& propertyNameVector() { return m_propertyNameVector; }
 
-        void setCachedStructure(Structure* structure) { m_cachedStructure = structure; }
-        Structure* cachedStructure() const { return m_cachedStructure; }
-
-        void setCachedPrototypeChain(NonNullPassRefPtr<StructureChain> cachedPrototypeChain) { m_cachedPrototypeChain = cachedPrototypeChain; }
-        StructureChain* cachedPrototypeChain() { return m_cachedPrototypeChain.get(); }
-
     private:
         PropertyNameArrayData()
-            : m_cachedStructure(0)
         {
         }
 
         PropertyNameVector m_propertyNameVector;
-        Structure* m_cachedStructure;
-        RefPtr<StructureChain> m_cachedPrototypeChain;
     };
 
+    // FIXME: Rename to PropertyNameArrayBuilder.
     class PropertyNameArray {
     public:
-        typedef PropertyNameArrayData::const_iterator const_iterator;
-
         PropertyNameArray(JSGlobalData* globalData)
             : m_data(PropertyNameArrayData::create())
             , m_globalData(globalData)
@@ -82,21 +72,18 @@ namespace JSC {
         void add(UString::Rep*);
         void addKnownUnique(UString::Rep* identifier) { m_data->propertyNameVector().append(Identifier(m_globalData, identifier)); }
 
-        size_t size() const { return m_data->propertyNameVector().size(); }
-
         Identifier& operator[](unsigned i) { return m_data->propertyNameVector()[i]; }
         const Identifier& operator[](unsigned i) const { return m_data->propertyNameVector()[i]; }
 
-        const_iterator begin() const { return m_data->begin(); }
-        const_iterator end() const { return m_data->end(); }
-
         void setData(PassRefPtr<PropertyNameArrayData> data) { m_data = data; }
         PropertyNameArrayData* data() { return m_data.get(); }
-
         PassRefPtr<PropertyNameArrayData> releaseData() { return m_data.release(); }
 
-        void setShouldCache(bool shouldCache) { m_shouldCache = shouldCache; }
-        bool shouldCache() const { return m_shouldCache; }
+        // FIXME: Remove these functions.
+        typedef PropertyNameArrayData::PropertyNameVector::const_iterator const_iterator;
+        size_t size() const { return m_data->propertyNameVector().size(); }
+        const_iterator begin() const { return m_data->propertyNameVector().begin(); }
+        const_iterator end() const { return m_data->propertyNameVector().end(); }
 
     private:
         typedef HashSet<UString::Rep*, PtrHash<UString::Rep*> > IdentifierSet;
diff --git a/JavaScriptCore/runtime/Protect.h b/JavaScriptCore/runtime/Protect.h
index 224164d..a0d5443 100644
--- a/JavaScriptCore/runtime/Protect.h
+++ b/JavaScriptCore/runtime/Protect.h
@@ -22,8 +22,8 @@
 #ifndef Protect_h
 #define Protect_h
 
-#include "JSCell.h"
 #include "Collector.h"
+#include "JSValue.h"
 
 namespace JSC {
 
diff --git a/JavaScriptCore/runtime/RegExpConstructor.cpp b/JavaScriptCore/runtime/RegExpConstructor.cpp
index dbf2d44..c609e08 100644
--- a/JavaScriptCore/runtime/RegExpConstructor.cpp
+++ b/JavaScriptCore/runtime/RegExpConstructor.cpp
@@ -90,28 +90,6 @@ const ClassInfo RegExpConstructor::info = { "Function", &InternalFunction::info,
 @end
 */
 
-struct RegExpConstructorPrivate : FastAllocBase {
-    // Global search cache / settings
-    RegExpConstructorPrivate()
-        : lastNumSubPatterns(0)
-        , multiline(false)
-        , lastOvectorIndex(0)
-    {
-    }
-
-    const Vector<int, 32>& lastOvector() const { return ovector[lastOvectorIndex]; }
-    Vector<int, 32>& lastOvector() { return ovector[lastOvectorIndex]; }
-    Vector<int, 32>& tempOvector() { return ovector[lastOvectorIndex ? 0 : 1]; }
-    void changeLastOvector() { lastOvectorIndex = lastOvectorIndex ? 0 : 1; }
-
-    UString input;
-    UString lastInput;
-    Vector<int, 32> ovector[2];
-    unsigned lastNumSubPatterns : 30;
-    bool multiline : 1;
-    unsigned lastOvectorIndex : 1;
-};
-
 RegExpConstructor::RegExpConstructor(ExecState* exec, NonNullPassRefPtr<Structure> structure, RegExpPrototype* regExpPrototype)
     : InternalFunction(&exec->globalData(), structure, Identifier(exec, "RegExp"))
     , d(new RegExpConstructorPrivate)
@@ -123,30 +101,6 @@ RegExpConstructor::RegExpConstructor(ExecState* exec, NonNullPassRefPtr<Structur
     putDirectWithoutTransition(exec->propertyNames().length, jsNumber(exec, 2), ReadOnly | DontDelete | DontEnum);
 }
 
-/* 
-  To facilitate result caching, exec(), test(), match(), search(), and replace() dipatch regular
-  expression matching through the performMatch function. We use cached results to calculate, 
-  e.g., RegExp.lastMatch and RegExp.leftParen.
-*/
-void RegExpConstructor::performMatch(RegExp* r, const UString& s, int startOffset, int& position, int& length, int** ovector)
-{
-    position = r->match(s, startOffset, &d->tempOvector());
-
-    if (ovector)
-        *ovector = d->tempOvector().data();
-
-    if (position != -1) {
-        ASSERT(!d->tempOvector().isEmpty());
-
-        length = d->tempOvector()[1] - d->tempOvector()[0];
-
-        d->input = s;
-        d->lastInput = s;
-        d->changeLastOvector();
-        d->lastNumSubPatterns = r->numSubpatterns();
-    }
-}
-
 RegExpMatchesArray::RegExpMatchesArray(ExecState* exec, RegExpConstructorPrivate* data)
     : JSArray(exec->lexicalGlobalObject()->regExpMatchesArrayStructure(), data->lastNumSubPatterns + 1)
 {
diff --git a/JavaScriptCore/runtime/RegExpConstructor.h b/JavaScriptCore/runtime/RegExpConstructor.h
index f8bccf4..f9ca9cf 100644
--- a/JavaScriptCore/runtime/RegExpConstructor.h
+++ b/JavaScriptCore/runtime/RegExpConstructor.h
@@ -22,6 +22,7 @@
 #define RegExpConstructor_h
 
 #include "InternalFunction.h"
+#include "RegExp.h"
 #include <wtf/OwnPtr.h>
 
 namespace JSC {
@@ -30,13 +31,35 @@ namespace JSC {
     class RegExpPrototype;
     struct RegExpConstructorPrivate;
 
+    struct RegExpConstructorPrivate : FastAllocBase {
+        // Global search cache / settings
+        RegExpConstructorPrivate()
+            : lastNumSubPatterns(0)
+            , multiline(false)
+            , lastOvectorIndex(0)
+        {
+        }
+
+        const Vector<int, 32>& lastOvector() const { return ovector[lastOvectorIndex]; }
+        Vector<int, 32>& lastOvector() { return ovector[lastOvectorIndex]; }
+        Vector<int, 32>& tempOvector() { return ovector[lastOvectorIndex ? 0 : 1]; }
+        void changeLastOvector() { lastOvectorIndex = lastOvectorIndex ? 0 : 1; }
+
+        UString input;
+        UString lastInput;
+        Vector<int, 32> ovector[2];
+        unsigned lastNumSubPatterns : 30;
+        bool multiline : 1;
+        unsigned lastOvectorIndex : 1;
+    };
+
     class RegExpConstructor : public InternalFunction {
     public:
         RegExpConstructor(ExecState*, NonNullPassRefPtr<Structure>, RegExpPrototype*);
 
         static PassRefPtr<Structure> createStructure(JSValue prototype)
         {
-            return Structure::create(prototype, TypeInfo(ObjectType, ImplementsHasInstance | HasDefaultMark | HasDefaultGetPropertyNames));
+            return Structure::create(prototype, TypeInfo(ObjectType, StructureFlags));
         }
 
         virtual void put(ExecState*, const Identifier& propertyName, JSValue, PutPropertySlot&);
@@ -59,6 +82,9 @@ namespace JSC {
         JSValue getLeftContext(ExecState*) const;
         JSValue getRightContext(ExecState*) const;
 
+    protected:
+        static const unsigned StructureFlags = OverridesGetOwnPropertySlot | ImplementsHasInstance | InternalFunction::StructureFlags;
+
     private:
         virtual ConstructType getConstructData(ConstructData&);
         virtual CallType getCallData(CallData&);
@@ -78,6 +104,30 @@ namespace JSC {
         return static_cast<RegExpConstructor*>(asObject(value));
     }
 
+    /* 
+      To facilitate result caching, exec(), test(), match(), search(), and replace() dipatch regular
+      expression matching through the performMatch function. We use cached results to calculate, 
+      e.g., RegExp.lastMatch and RegExp.leftParen.
+    */
+    inline void RegExpConstructor::performMatch(RegExp* r, const UString& s, int startOffset, int& position, int& length, int** ovector)
+    {
+        position = r->match(s, startOffset, &d->tempOvector());
+
+        if (ovector)
+            *ovector = d->tempOvector().data();
+
+        if (position != -1) {
+            ASSERT(!d->tempOvector().isEmpty());
+
+            length = d->tempOvector()[1] - d->tempOvector()[0];
+
+            d->input = s;
+            d->lastInput = s;
+            d->changeLastOvector();
+            d->lastNumSubPatterns = r->numSubpatterns();
+        }
+    }
+
 } // namespace JSC
 
 #endif // RegExpConstructor_h
diff --git a/JavaScriptCore/runtime/RegExpObject.cpp b/JavaScriptCore/runtime/RegExpObject.cpp
index 877d7b6..679d072 100644
--- a/JavaScriptCore/runtime/RegExpObject.cpp
+++ b/JavaScriptCore/runtime/RegExpObject.cpp
@@ -159,7 +159,7 @@ bool RegExpObject::match(ExecState* exec, const ArgList& args)
     }
 
     int position;
-    int length;
+    int length = 0;
     regExpConstructor->performMatch(d->regExp.get(), input, static_cast<int>(d->lastIndex), position, length);
     if (position < 0) {
         d->lastIndex = 0;
diff --git a/JavaScriptCore/runtime/RegExpObject.h b/JavaScriptCore/runtime/RegExpObject.h
index f5a9340..3117c86 100644
--- a/JavaScriptCore/runtime/RegExpObject.h
+++ b/JavaScriptCore/runtime/RegExpObject.h
@@ -49,9 +49,12 @@ namespace JSC {
 
         static PassRefPtr<Structure> createStructure(JSValue prototype)
         {
-            return Structure::create(prototype, TypeInfo(ObjectType, HasDefaultMark | HasDefaultGetPropertyNames));
+            return Structure::create(prototype, TypeInfo(ObjectType, StructureFlags));
         }
 
+    protected:
+        static const unsigned StructureFlags = OverridesGetOwnPropertySlot | JSObject::StructureFlags;
+
     private:
         bool match(ExecState*, const ArgList&);
 
diff --git a/JavaScriptCore/runtime/StringObject.h b/JavaScriptCore/runtime/StringObject.h
index 944f6ba..84e1ad2 100644
--- a/JavaScriptCore/runtime/StringObject.h
+++ b/JavaScriptCore/runtime/StringObject.h
@@ -48,10 +48,11 @@ namespace JSC {
 
         static PassRefPtr<Structure> createStructure(JSValue prototype)
         {
-            return Structure::create(prototype, TypeInfo(ObjectType));
+            return Structure::create(prototype, TypeInfo(ObjectType, StructureFlags));
         }
 
     protected:
+        static const unsigned StructureFlags = OverridesGetOwnPropertySlot | OverridesMarkChildren | OverridesGetPropertyNames | JSWrapperObject::StructureFlags;
         StringObject(NonNullPassRefPtr<Structure>, JSString*);
   };
 
diff --git a/JavaScriptCore/runtime/StringObjectThatMasqueradesAsUndefined.h b/JavaScriptCore/runtime/StringObjectThatMasqueradesAsUndefined.h
index 0cba83d..69e1939 100644
--- a/JavaScriptCore/runtime/StringObjectThatMasqueradesAsUndefined.h
+++ b/JavaScriptCore/runtime/StringObjectThatMasqueradesAsUndefined.h
@@ -44,9 +44,11 @@ namespace JSC {
 
         static PassRefPtr<Structure> createStructure(JSValue proto) 
         { 
-            return Structure::create(proto, TypeInfo(ObjectType, MasqueradesAsUndefined | HasDefaultMark)); 
+            return Structure::create(proto, TypeInfo(ObjectType, StructureFlags)); 
         }
 
+        static const unsigned StructureFlags = OverridesGetOwnPropertySlot | MasqueradesAsUndefined | OverridesGetPropertyNames | StringObject::StructureFlags;
+
         virtual bool toBoolean(ExecState*) const { return false; }
     };
  
diff --git a/JavaScriptCore/runtime/StringPrototype.cpp b/JavaScriptCore/runtime/StringPrototype.cpp
index b57732a..a0713b8 100644
--- a/JavaScriptCore/runtime/StringPrototype.cpp
+++ b/JavaScriptCore/runtime/StringPrototype.cpp
@@ -25,6 +25,7 @@
 #include "CachedCall.h"
 #include "Error.h"
 #include "Executable.h"
+#include "JSGlobalObjectFunctions.h"
 #include "JSArray.h"
 #include "JSFunction.h"
 #include "ObjectPrototype.h"
@@ -72,6 +73,10 @@ static JSValue JSC_HOST_CALL stringProtoFuncFontsize(ExecState*, JSObject*, JSVa
 static JSValue JSC_HOST_CALL stringProtoFuncAnchor(ExecState*, JSObject*, JSValue, const ArgList&);
 static JSValue JSC_HOST_CALL stringProtoFuncLink(ExecState*, JSObject*, JSValue, const ArgList&);
 
+static JSValue JSC_HOST_CALL stringProtoFuncTrim(ExecState*, JSObject*, JSValue, const ArgList&);
+static JSValue JSC_HOST_CALL stringProtoFuncTrimLeft(ExecState*, JSObject*, JSValue, const ArgList&);
+static JSValue JSC_HOST_CALL stringProtoFuncTrimRight(ExecState*, JSObject*, JSValue, const ArgList&);
+
 }
 
 #include "StringPrototype.lut.h"
@@ -117,6 +122,9 @@ const ClassInfo StringPrototype::info = { "String", &StringObject::info, 0, Exec
     fontsize              stringProtoFuncFontsize          DontEnum|Function       1
     anchor                stringProtoFuncAnchor            DontEnum|Function       1
     link                  stringProtoFuncLink              DontEnum|Function       1
+    trim                  stringProtoFuncTrim              DontEnum|Function       0
+    trimLeft              stringProtoFuncTrimLeft          DontEnum|Function       0
+    trimRight             stringProtoFuncTrimRight         DontEnum|Function       0
 @end
 */
 
@@ -249,7 +257,7 @@ JSValue JSC_HOST_CALL stringProtoFuncReplace(ExecState* exec, JSObject*, JSValue
                 return jsNull();
             while (true) {
                 int matchIndex;
-                int matchLen;
+                int matchLen = 0;
                 int* ovector;
                 regExpConstructor->performMatch(reg, source, startPosition, matchIndex, matchLen, &ovector);
                 if (matchIndex < 0)
@@ -290,7 +298,7 @@ JSValue JSC_HOST_CALL stringProtoFuncReplace(ExecState* exec, JSObject*, JSValue
         } else {
             do {
                 int matchIndex;
-                int matchLen;
+                int matchLen = 0;
                 int* ovector;
                 regExpConstructor->performMatch(reg, source, startPosition, matchIndex, matchLen, &ovector);
                 if (matchIndex < 0)
@@ -485,7 +493,7 @@ JSValue JSC_HOST_CALL stringProtoFuncMatch(ExecState* exec, JSObject*, JSValue t
     }
     RegExpConstructor* regExpConstructor = exec->lexicalGlobalObject()->regExpConstructor();
     int pos;
-    int matchLength;
+    int matchLength = 0;
     regExpConstructor->performMatch(reg.get(), u, 0, pos, matchLength);
     if (!(reg->global())) {
         // case without 'g' flag is handled like RegExp.prototype.exec
@@ -535,7 +543,7 @@ JSValue JSC_HOST_CALL stringProtoFuncSearch(ExecState* exec, JSObject*, JSValue
     }
     RegExpConstructor* regExpConstructor = exec->lexicalGlobalObject()->regExpConstructor();
     int pos;
-    int matchLength;
+    int matchLength = 0;
     regExpConstructor->performMatch(reg.get(), u, 0, pos, matchLength);
     return jsNumber(exec, pos);
 }
@@ -899,4 +907,51 @@ JSValue JSC_HOST_CALL stringProtoFuncLink(ExecState* exec, JSObject*, JSValue th
     return jsNontrivialString(exec, UString(buffer, bufferSize, false));
 }
 
+enum {
+    TrimLeft = 1,
+    TrimRight = 2
+};
+
+static inline bool isTrimWhitespace(UChar c)
+{
+    return isStrWhiteSpace(c) || c == 0x200b;
+}
+
+static inline JSValue trimString(ExecState* exec, JSValue thisValue, int trimKind)
+{
+    UString str = thisValue.toThisString(exec);
+    int left = 0;
+    if (trimKind & TrimLeft) {
+        while (left < str.size() && isTrimWhitespace(str[left]))
+            left++;
+    }
+    int right = str.size();
+    if (trimKind & TrimRight) {
+        while (right > left && isTrimWhitespace(str[right - 1]))
+            right--;
+    }
+
+    // Don't gc allocate a new string if we don't have to.
+    if (left == 0 && right == str.size() && thisValue.isString())
+        return thisValue;
+
+    return jsString(exec, str.substr(left, right - left));
+}
+
+JSValue JSC_HOST_CALL stringProtoFuncTrim(ExecState* exec, JSObject*, JSValue thisValue, const ArgList&)
+{
+    return trimString(exec, thisValue, TrimLeft | TrimRight);
+}
+
+JSValue JSC_HOST_CALL stringProtoFuncTrimLeft(ExecState* exec, JSObject*, JSValue thisValue, const ArgList&)
+{
+    return trimString(exec, thisValue, TrimLeft);
+}
+
+JSValue JSC_HOST_CALL stringProtoFuncTrimRight(ExecState* exec, JSObject*, JSValue thisValue, const ArgList&)
+{
+    return trimString(exec, thisValue, TrimRight);
+}
+    
+    
 } // namespace JSC
diff --git a/JavaScriptCore/runtime/Structure.cpp b/JavaScriptCore/runtime/Structure.cpp
index 7209b5f..65b62f9 100644
--- a/JavaScriptCore/runtime/Structure.cpp
+++ b/JavaScriptCore/runtime/Structure.cpp
@@ -28,9 +28,10 @@
 
 #include "Identifier.h"
 #include "JSObject.h"
+#include "JSPropertyNameIterator.h"
+#include "Lookup.h"
 #include "PropertyNameArray.h"
 #include "StructureChain.h"
-#include "Lookup.h"
 #include <wtf/RefCountedLeakCounter.h>
 #include <wtf/RefPtr.h>
 
@@ -159,9 +160,9 @@ Structure::~Structure()
             m_previous->table.removeAnonymousSlotTransition(m_anonymousSlotsInPrevious);
 
     }
-
-    if (m_cachedPropertyNameArrayData)
-        m_cachedPropertyNameArrayData->setCachedStructure(0);
+    
+    if (m_enumerationCache)
+        m_enumerationCache->setCachedStructure(0);
 
     if (m_propertyTable) {
         unsigned entryCount = m_propertyTable->keyCount + m_propertyTable->deletedSentinelCount;
@@ -282,59 +283,6 @@ void Structure::materializePropertyMap()
     }
 }
 
-void Structure::getOwnEnumerablePropertyNames(ExecState* exec, PropertyNameArray& propertyNames, JSObject* baseObject)
-{
-    getEnumerableNamesFromPropertyTable(propertyNames);
-    getEnumerableNamesFromClassInfoTable(exec, baseObject->classInfo(), propertyNames);
-}
-
-void Structure::getEnumerablePropertyNames(ExecState* exec, PropertyNameArray& propertyNames, JSObject* baseObject)
-{
-    bool shouldCache = propertyNames.shouldCache() && !(propertyNames.size() || isDictionary());
-
-    if (shouldCache && m_cachedPropertyNameArrayData) {
-        if (m_cachedPropertyNameArrayData->cachedPrototypeChain() == prototypeChain(exec)) {
-            propertyNames.setData(m_cachedPropertyNameArrayData);
-            return;
-        }
-        clearEnumerationCache();
-    }
-
-    baseObject->getOwnPropertyNames(exec, propertyNames);
-
-    if (m_prototype.isObject()) {
-        propertyNames.setShouldCache(false); // No need for our prototypes to waste memory on caching, since they're not being enumerated directly.
-        JSObject* prototype = asObject(m_prototype);
-        while(1) {
-            if (!prototype->structure()->typeInfo().hasDefaultGetPropertyNames()) {
-                prototype->getPropertyNames(exec, propertyNames);
-                break;
-            }
-            prototype->getOwnPropertyNames(exec, propertyNames);
-            JSValue nextProto = prototype->prototype();
-            if (!nextProto.isObject())
-                break;
-            prototype = asObject(nextProto);
-        }
-    }
-
-    if (shouldCache) {
-        StructureChain* protoChain = prototypeChain(exec);
-        m_cachedPropertyNameArrayData = propertyNames.data();
-        if (!protoChain->isCacheable())
-            return;
-        m_cachedPropertyNameArrayData->setCachedPrototypeChain(protoChain);
-        m_cachedPropertyNameArrayData->setCachedStructure(this);
-    }
-}
-
-void Structure::clearEnumerationCache()
-{
-    if (m_cachedPropertyNameArrayData)
-        m_cachedPropertyNameArrayData->setCachedStructure(0);
-    m_cachedPropertyNameArrayData.clear();
-}
-
 void Structure::growPropertyStorageCapacity()
 {
     if (m_propertyStorageCapacity == JSObject::inlineStorageCapacity)
@@ -427,6 +375,7 @@ PassRefPtr<Structure> Structure::addPropertyTransition(Structure* structure, con
     transition->m_specificValueInPrevious = specificValue;
     transition->m_propertyStorageCapacity = structure->m_propertyStorageCapacity;
     transition->m_hasGetterSetterProperties = structure->m_hasGetterSetterProperties;
+    transition->m_hasNonEnumerableProperties = structure->m_hasNonEnumerableProperties;
 
     if (structure->m_propertyTable) {
         if (structure->m_isPinnedPropertyTable)
@@ -469,6 +418,7 @@ PassRefPtr<Structure> Structure::changePrototypeTransition(Structure* structure,
 
     transition->m_propertyStorageCapacity = structure->m_propertyStorageCapacity;
     transition->m_hasGetterSetterProperties = structure->m_hasGetterSetterProperties;
+    transition->m_hasNonEnumerableProperties = structure->m_hasNonEnumerableProperties;
 
     // Don't set m_offset, as one can not transition to this.
 
@@ -485,6 +435,7 @@ PassRefPtr<Structure> Structure::despecifyFunctionTransition(Structure* structur
 
     transition->m_propertyStorageCapacity = structure->m_propertyStorageCapacity;
     transition->m_hasGetterSetterProperties = structure->m_hasGetterSetterProperties;
+    transition->m_hasNonEnumerableProperties = structure->m_hasNonEnumerableProperties;
 
     // Don't set m_offset, as one can not transition to this.
 
@@ -516,6 +467,7 @@ PassRefPtr<Structure> Structure::addAnonymousSlotsTransition(Structure* structur
     transition->m_specificValueInPrevious = 0;
     transition->m_propertyStorageCapacity = structure->m_propertyStorageCapacity;
     transition->m_hasGetterSetterProperties = structure->m_hasGetterSetterProperties;
+    transition->m_hasNonEnumerableProperties = structure->m_hasNonEnumerableProperties;
 
     if (structure->m_propertyTable) {
         if (structure->m_isPinnedPropertyTable)
@@ -544,6 +496,7 @@ PassRefPtr<Structure> Structure::getterSetterTransition(Structure* structure)
     RefPtr<Structure> transition = create(structure->storedPrototype(), structure->typeInfo());
     transition->m_propertyStorageCapacity = structure->m_propertyStorageCapacity;
     transition->m_hasGetterSetterProperties = transition->m_hasGetterSetterProperties;
+    transition->m_hasNonEnumerableProperties = structure->m_hasNonEnumerableProperties;
 
     // Don't set m_offset, as one can not transition to this.
 
@@ -562,6 +515,7 @@ PassRefPtr<Structure> Structure::toDictionaryTransition(Structure* structure, Di
     transition->m_dictionaryKind = kind;
     transition->m_propertyStorageCapacity = structure->m_propertyStorageCapacity;
     transition->m_hasGetterSetterProperties = structure->m_hasGetterSetterProperties;
+    transition->m_hasNonEnumerableProperties = structure->m_hasNonEnumerableProperties;
     
     structure->materializePropertyMapIfNecessary();
     transition->m_propertyTable = structure->copyPropertyTable();
@@ -598,25 +552,28 @@ PassRefPtr<Structure> Structure::fromDictionaryTransition(Structure* structure)
 
 size_t Structure::addPropertyWithoutTransition(const Identifier& propertyName, unsigned attributes, JSCell* specificValue)
 {
+    ASSERT(!m_enumerationCache);
     materializePropertyMapIfNecessary();
 
     m_isPinnedPropertyTable = true;
+    if (attributes & DontEnum)
+        m_hasNonEnumerableProperties = true;
+
     size_t offset = put(propertyName, attributes, specificValue);
     if (propertyStorageSize() > propertyStorageCapacity())
         growPropertyStorageCapacity();
-    clearEnumerationCache();
     return offset;
 }
 
 size_t Structure::removePropertyWithoutTransition(const Identifier& propertyName)
 {
     ASSERT(isUncacheableDictionary());
+    ASSERT(!m_enumerationCache);
 
     materializePropertyMapIfNecessary();
 
     m_isPinnedPropertyTable = true;
     size_t offset = remove(propertyName);
-    clearEnumerationCache();
     return offset;
 }
 
@@ -1057,7 +1014,7 @@ static int comparePropertyMapEntryIndices(const void* a, const void* b)
     return 0;
 }
 
-void Structure::getEnumerableNamesFromPropertyTable(PropertyNameArray& propertyNames)
+void Structure::getEnumerablePropertyNames(PropertyNameArray& propertyNames)
 {
     materializePropertyMapIfNecessary();
     if (!m_propertyTable)
@@ -1114,25 +1071,6 @@ void Structure::getEnumerableNamesFromPropertyTable(PropertyNameArray& propertyN
     }
 }
 
-void Structure::getEnumerableNamesFromClassInfoTable(ExecState* exec, const ClassInfo* classInfo, PropertyNameArray& propertyNames)
-{
-    // Add properties from the static hashtables of properties
-    for (; classInfo; classInfo = classInfo->parentClass) {
-        const HashTable* table = classInfo->propHashTable(exec);
-        if (!table)
-            continue;
-        table->initializeIfNeeded(exec);
-        ASSERT(table->table);
-
-        int hashSizeMask = table->compactSize - 1;
-        const HashEntry* entry = table->table;
-        for (int i = 0; i <= hashSizeMask; ++i, ++entry) {
-            if (entry->key() && !(entry->attributes() & DontEnum))
-                propertyNames.add(entry->key());
-        }
-    }
-}
-
 #if DO_PROPERTYMAP_CONSTENCY_CHECK
 
 void Structure::checkConsistency()
diff --git a/JavaScriptCore/runtime/Structure.h b/JavaScriptCore/runtime/Structure.h
index ed9f6e5..f355c53 100644
--- a/JavaScriptCore/runtime/Structure.h
+++ b/JavaScriptCore/runtime/Structure.h
@@ -30,6 +30,8 @@
 #include "JSType.h"
 #include "JSValue.h"
 #include "PropertyMapHashTable.h"
+#include "PropertyNameArray.h"
+#include "Protect.h"
 #include "StructureChain.h"
 #include "StructureTransitionTable.h"
 #include "JSTypeInfo.h"
@@ -76,8 +78,6 @@ namespace JSC {
 
         ~Structure();
 
-        void markAggregate(MarkStack&);
-
         // These should be used with caution.  
         size_t addPropertyWithoutTransition(const Identifier& propertyName, unsigned attributes, JSCell* specificValue);
         size_t removePropertyWithoutTransition(const Identifier& propertyName);
@@ -95,8 +95,8 @@ namespace JSC {
         Structure* previousID() const { return m_previous.get(); }
 
         void growPropertyStorageCapacity();
-        size_t propertyStorageCapacity() const { return m_propertyStorageCapacity; }
-        size_t propertyStorageSize() const { return m_propertyTable ? m_propertyTable->keyCount + m_propertyTable->anonymousSlotCount + (m_propertyTable->deletedOffsets ? m_propertyTable->deletedOffsets->size() : 0) : m_offset + 1; }
+        unsigned propertyStorageCapacity() const { return m_propertyStorageCapacity; }
+        unsigned propertyStorageSize() const { return m_propertyTable ? m_propertyTable->keyCount + m_propertyTable->anonymousSlotCount + (m_propertyTable->deletedOffsets ? m_propertyTable->deletedOffsets->size() : 0) : m_offset + 1; }
         bool isUsingInlineStorage() const;
 
         size_t get(const Identifier& propertyName);
@@ -116,17 +116,22 @@ namespace JSC {
             return hasTransition(propertyName._ustring.rep(), attributes);
         }
 
-        void getEnumerablePropertyNames(ExecState*, PropertyNameArray&, JSObject*);
-        void getOwnEnumerablePropertyNames(ExecState*, PropertyNameArray&, JSObject*);
-
         bool hasGetterSetterProperties() const { return m_hasGetterSetterProperties; }
         void setHasGetterSetterProperties(bool hasGetterSetterProperties) { m_hasGetterSetterProperties = hasGetterSetterProperties; }
 
+        bool hasNonEnumerableProperties() const { return m_hasNonEnumerableProperties; }
+
+        bool hasAnonymousSlots() const { return m_propertyTable && m_propertyTable->anonymousSlotCount; }
+        
         bool isEmpty() const { return m_propertyTable ? !m_propertyTable->keyCount : m_offset == noOffset; }
 
         JSCell* specificValue() { return m_specificValueInPrevious; }
         void despecifyDictionaryFunction(const Identifier& propertyName);
 
+        void setEnumerationCache(JSPropertyNameIterator* enumerationCache); // Defined in JSPropertyNameIterator.h.
+        JSPropertyNameIterator* enumerationCache() { return m_enumerationCache.get(); }
+        void getEnumerablePropertyNames(PropertyNameArray&);
+
     private:
         Structure(JSValue prototype, const TypeInfo&);
         
@@ -140,8 +145,6 @@ namespace JSC {
         size_t put(const Identifier& propertyName, unsigned attributes, JSCell* specificValue);
         size_t remove(const Identifier& propertyName);
         void addAnonymousSlots(unsigned slotCount);
-        void getEnumerableNamesFromPropertyTable(PropertyNameArray&);
-        void getEnumerableNamesFromClassInfoTable(ExecState*, const ClassInfo*, PropertyNameArray&);
 
         void expandPropertyMapHashTable();
         void rehashPropertyMapHashTable();
@@ -162,8 +165,6 @@ namespace JSC {
             materializePropertyMap();
         }
 
-        void clearEnumerationCache();
-
         signed char transitionCount() const
         {
             // Since the number of transitions is always the same as m_offset, we keep the size of Structure down by not storing both.
@@ -189,16 +190,17 @@ namespace JSC {
 
         StructureTransitionTable table;
 
-        RefPtr<PropertyNameArrayData> m_cachedPropertyNameArrayData;
+        ProtectedPtr<JSPropertyNameIterator> m_enumerationCache;
 
         PropertyMapHashTable* m_propertyTable;
 
-        size_t m_propertyStorageCapacity;
+        uint32_t m_propertyStorageCapacity;
         signed char m_offset;
 
         unsigned m_dictionaryKind : 2;
         bool m_isPinnedPropertyTable : 1;
         bool m_hasGetterSetterProperties : 1;
+        bool m_hasNonEnumerableProperties : 1;
 #if COMPILER(WINSCW)
         // Workaround for Symbian WINSCW compiler that cannot resolve unsigned type of the declared 
         // bitfield, when used as argument in make_pair() function calls in structure.ccp.
diff --git a/JavaScriptCore/runtime/StructureChain.cpp b/JavaScriptCore/runtime/StructureChain.cpp
index 6e8a0ee..085876c 100644
--- a/JavaScriptCore/runtime/StructureChain.cpp
+++ b/JavaScriptCore/runtime/StructureChain.cpp
@@ -46,18 +46,4 @@ StructureChain::StructureChain(Structure* head)
     m_vector[i] = 0;
 }
 
-bool StructureChain::isCacheable() const
-{
-    uint32_t i = 0;
-    
-    while (m_vector[i]) {
-        // Both classes of dictionary structure may change arbitrarily so we can't cache them
-        if (m_vector[i]->isDictionary())
-            return false;
-        if (!m_vector[i++]->typeInfo().hasDefaultGetPropertyNames())
-            return false;
-    }
-    return true;
-}
-
 } // namespace JSC
diff --git a/JavaScriptCore/runtime/StructureChain.h b/JavaScriptCore/runtime/StructureChain.h
index c48749d..816b66d 100644
--- a/JavaScriptCore/runtime/StructureChain.h
+++ b/JavaScriptCore/runtime/StructureChain.h
@@ -36,10 +36,11 @@ namespace JSC {
     class Structure;
 
     class StructureChain : public RefCounted<StructureChain> {
+        friend class JIT;
+
     public:
         static PassRefPtr<StructureChain> create(Structure* head) { return adoptRef(new StructureChain(head)); }
         RefPtr<Structure>* head() { return m_vector.get(); }
-        bool isCacheable() const;
 
     private:
         StructureChain(Structure* head);