Merge webkit.org at r54127 : Initial merge by git

Change-Id: Ib661abb595522f50ea406f72d3a0ce17f7193c82

17 files changed, 350 insertions, 197 deletions

diff --git a/JavaScriptCore/API/APIShims.h b/JavaScriptCore/API/APIShims.h
new file mode 100644
index 0000000..d7276ec
--- /dev/null
+++ b/JavaScriptCore/API/APIShims.h
@@ -0,0 +1,99 @@
+/*
+ * 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 COMPUTER, 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 COMPUTER, 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 APIShims_h
+#define APIShims_h
+
+#include "CallFrame.h"
+#include "JSLock.h"
+
+namespace JSC {
+
+class APIEntryShimWithoutLock {
+protected:
+    APIEntryShimWithoutLock(JSGlobalData* globalData, bool registerThread)
+        : m_globalData(globalData)
+        , m_entryIdentifierTable(setCurrentIdentifierTable(globalData->identifierTable))
+    {
+        if (registerThread)
+            globalData->heap.registerThread();
+        m_globalData->timeoutChecker.start();
+    }
+
+    ~APIEntryShimWithoutLock()
+    {
+        m_globalData->timeoutChecker.stop();
+        setCurrentIdentifierTable(m_entryIdentifierTable);
+    }
+
+private:
+    JSGlobalData* m_globalData;
+    IdentifierTable* m_entryIdentifierTable;
+};
+
+class APIEntryShim : public APIEntryShimWithoutLock {
+public:
+    // Normal API entry
+    APIEntryShim(ExecState* exec, bool registerThread = true)
+        : APIEntryShimWithoutLock(&exec->globalData(), registerThread)
+        , m_lock(exec)
+    {
+    }
+
+    // JSPropertyNameAccumulator only has a globalData.
+    APIEntryShim(JSGlobalData* globalData, bool registerThread = true)
+        : APIEntryShimWithoutLock(globalData, registerThread)
+        , m_lock(globalData->isSharedInstance ? LockForReal : SilenceAssertionsOnly)
+    {
+    }
+
+private:
+    JSLock m_lock;
+};
+
+class APICallbackShim {
+public:
+    APICallbackShim(ExecState* exec)
+        : m_dropAllLocks(exec)
+        , m_globalData(&exec->globalData())
+    {
+        resetCurrentIdentifierTable();
+        m_globalData->timeoutChecker.start();
+    }
+
+    ~APICallbackShim()
+    {
+        m_globalData->timeoutChecker.stop();
+        setCurrentIdentifierTable(m_globalData->identifierTable);
+    }
+
+private:
+    JSLock::DropAllLocks m_dropAllLocks;
+    JSGlobalData* m_globalData;
+};
+
+}
+
+#endif
diff --git a/JavaScriptCore/API/JSBase.cpp b/JavaScriptCore/API/JSBase.cpp
index 4a32d35..ebfeafa 100644
--- a/JavaScriptCore/API/JSBase.cpp
+++ b/JavaScriptCore/API/JSBase.cpp
@@ -28,6 +28,7 @@
 #include "JSBasePrivate.h"
 
 #include "APICast.h"
+#include "APIShims.h"
 #include "Completion.h"
 #include "OpaqueJSString.h"
 #include "SourceCode.h"
@@ -43,8 +44,7 @@ using namespace JSC;
 JSValueRef JSEvaluateScript(JSContextRef ctx, JSStringRef script, JSObjectRef thisObject, JSStringRef sourceURL, int startingLineNumber, JSValueRef* exception)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSObject* jsThisObject = toJS(thisObject);
 
@@ -69,8 +69,7 @@ JSValueRef JSEvaluateScript(JSContextRef ctx, JSStringRef script, JSObjectRef th
 bool JSCheckScriptSyntax(JSContextRef ctx, JSStringRef script, JSStringRef sourceURL, int startingLineNumber, JSValueRef* exception)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     SourceCode source = makeSource(script->ustring(), sourceURL->ustring(), startingLineNumber);
     Completion completion = checkSyntax(exec->dynamicGlobalObject()->globalExec(), source);
@@ -94,12 +93,11 @@ void JSGarbageCollect(JSContextRef ctx)
         return;
 
     ExecState* exec = toJS(ctx);
-    JSGlobalData& globalData = exec->globalData();
-
-    JSLock lock(globalData.isSharedInstance ? LockForReal : SilenceAssertionsOnly);
+    APIEntryShim entryShim(exec, false);
 
+    JSGlobalData& globalData = exec->globalData();
     if (!globalData.heap.isBusy())
-        globalData.heap.collect();
+        globalData.heap.collectAllGarbage();
 
     // FIXME: Perhaps we should trigger a second mark and sweep
     // once the garbage collector is done if this is called when
@@ -109,8 +107,6 @@ void JSGarbageCollect(JSContextRef ctx)
 void JSReportExtraMemoryCost(JSContextRef ctx, size_t size)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
-
+    APIEntryShim entryShim(exec);
     exec->globalData().heap.reportExtraMemoryCost(size);
 }
diff --git a/JavaScriptCore/API/JSBase.h b/JavaScriptCore/API/JSBase.h
index d1ce9b3..2e16720 100644
--- a/JavaScriptCore/API/JSBase.h
+++ b/JavaScriptCore/API/JSBase.h
@@ -65,27 +65,15 @@ typedef struct OpaqueJSValue* JSObjectRef;
 /* JavaScript symbol exports */
 
 #undef JS_EXPORT
-#if defined(BUILDING_WX__)
+#if defined(JS_NO_EXPORT)
     #define JS_EXPORT
 #elif defined(__GNUC__) && !defined(__CC_ARM) && !defined(__ARMCC__)
     #define JS_EXPORT __attribute__((visibility("default")))
-#elif defined(_WIN32_WCE)
-    #if defined(JS_BUILDING_JS)
-        #define JS_EXPORT __declspec(dllexport)
-    #elif defined(JS_IMPORT_JS)
-        #define JS_EXPORT __declspec(dllimport)
-    #else
-        #define JS_EXPORT
-    #endif
-#elif defined(WIN32) || defined(_WIN32)
-    /*
-     * TODO: Export symbols with JS_EXPORT when using MSVC.
-     * See http://bugs.webkit.org/show_bug.cgi?id=16227
-     */
+#elif defined(WIN32) || defined(_WIN32) || defined(_WIN32_WCE)
     #if defined(BUILDING_JavaScriptCore) || defined(BUILDING_WTF)
-    #define JS_EXPORT __declspec(dllexport)
+        #define JS_EXPORT __declspec(dllexport)
     #else
-    #define JS_EXPORT __declspec(dllimport)
+        #define JS_EXPORT __declspec(dllimport)
     #endif
 #else
     #define JS_EXPORT
diff --git a/JavaScriptCore/API/JSCallbackConstructor.cpp b/JavaScriptCore/API/JSCallbackConstructor.cpp
index 1c33962..9c5f6d7 100644
--- a/JavaScriptCore/API/JSCallbackConstructor.cpp
+++ b/JavaScriptCore/API/JSCallbackConstructor.cpp
@@ -26,6 +26,7 @@
 #include "config.h"
 #include "JSCallbackConstructor.h"
 
+#include "APIShims.h"
 #include "APICast.h"
 #include <runtime/JSGlobalObject.h>
 #include <runtime/JSLock.h>
@@ -66,7 +67,7 @@ static JSObject* constructJSCallback(ExecState* exec, JSObject* constructor, con
         JSValueRef exception = 0;
         JSObjectRef result;
         {
-            JSLock::DropAllLocks dropAllLocks(exec);
+            APICallbackShim callbackShim(exec);
             result = callback(ctx, constructorRef, argumentCount, arguments.data(), &exception);
         }
         if (exception)
diff --git a/JavaScriptCore/API/JSCallbackConstructor.h b/JavaScriptCore/API/JSCallbackConstructor.h
index c4bd7ad..e529947 100644
--- a/JavaScriptCore/API/JSCallbackConstructor.h
+++ b/JavaScriptCore/API/JSCallbackConstructor.h
@@ -41,7 +41,7 @@ public:
     
     static PassRefPtr<Structure> createStructure(JSValue proto) 
     { 
-        return Structure::create(proto, TypeInfo(ObjectType, StructureFlags)); 
+        return Structure::create(proto, TypeInfo(ObjectType, StructureFlags), AnonymousSlotCount); 
     }
 
 protected:
diff --git a/JavaScriptCore/API/JSCallbackFunction.cpp b/JavaScriptCore/API/JSCallbackFunction.cpp
index b7dd768..0e434d9 100644
--- a/JavaScriptCore/API/JSCallbackFunction.cpp
+++ b/JavaScriptCore/API/JSCallbackFunction.cpp
@@ -27,6 +27,7 @@
 #include <wtf/Platform.h>
 #include "JSCallbackFunction.h"
 
+#include "APIShims.h"
 #include "APICast.h"
 #include "CodeBlock.h"
 #include "JSFunction.h"
@@ -61,7 +62,7 @@ JSValue JSCallbackFunction::call(ExecState* exec, JSObject* functionObject, JSVa
     JSValueRef exception = 0;
     JSValueRef result;
     {
-        JSLock::DropAllLocks dropAllLocks(exec);
+        APICallbackShim callbackShim(exec);
         result = static_cast<JSCallbackFunction*>(functionObject)->m_callback(execRef, functionRef, thisObjRef, argumentCount, arguments.data(), &exception);
     }
     if (exception)
diff --git a/JavaScriptCore/API/JSCallbackFunction.h b/JavaScriptCore/API/JSCallbackFunction.h
index 0cf25c4..10dae6b 100644
--- a/JavaScriptCore/API/JSCallbackFunction.h
+++ b/JavaScriptCore/API/JSCallbackFunction.h
@@ -41,7 +41,7 @@ public:
     // refactor the code so this override isn't necessary
     static PassRefPtr<Structure> createStructure(JSValue proto) 
     { 
-        return Structure::create(proto, TypeInfo(ObjectType, StructureFlags)); 
+        return Structure::create(proto, TypeInfo(ObjectType, StructureFlags), AnonymousSlotCount); 
     }
 
 private:
diff --git a/JavaScriptCore/API/JSCallbackObject.h b/JavaScriptCore/API/JSCallbackObject.h
index d19890a..adb5b60 100644
--- a/JavaScriptCore/API/JSCallbackObject.h
+++ b/JavaScriptCore/API/JSCallbackObject.h
@@ -50,7 +50,7 @@ public:
 
     static PassRefPtr<Structure> createStructure(JSValue proto) 
     { 
-        return Structure::create(proto, TypeInfo(ObjectType, StructureFlags)); 
+        return Structure::create(proto, TypeInfo(ObjectType, StructureFlags), Base::AnonymousSlotCount); 
     }
 
 protected:
@@ -61,6 +61,7 @@ private:
 
     virtual bool getOwnPropertySlot(ExecState*, const Identifier&, PropertySlot&);
     virtual bool getOwnPropertySlot(ExecState*, unsigned, PropertySlot&);
+    virtual bool getOwnPropertyDescriptor(ExecState*, const Identifier&, PropertyDescriptor&);
     
     virtual void put(ExecState*, const Identifier&, JSValue, PutPropertySlot&);
 
@@ -69,7 +70,7 @@ private:
 
     virtual bool hasInstance(ExecState* exec, JSValue value, JSValue proto);
 
-    virtual void getOwnPropertyNames(ExecState*, PropertyNameArray&);
+    virtual void getOwnPropertyNames(ExecState*, PropertyNameArray&, EnumerationMode mode = ExcludeDontEnumProperties);
 
     virtual double toNumber(ExecState*) const;
     virtual UString toString(ExecState*) const;
diff --git a/JavaScriptCore/API/JSCallbackObjectFunctions.h b/JavaScriptCore/API/JSCallbackObjectFunctions.h
index ed86a00..4b28a99 100644
--- a/JavaScriptCore/API/JSCallbackObjectFunctions.h
+++ b/JavaScriptCore/API/JSCallbackObjectFunctions.h
@@ -24,6 +24,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
  */
 
+#include "APIShims.h"
 #include "APICast.h"
 #include "Error.h"
 #include "JSCallbackFunction.h"
@@ -79,7 +80,7 @@ void JSCallbackObject<Base>::init(ExecState* exec)
     
     // initialize from base to derived
     for (int i = static_cast<int>(initRoutines.size()) - 1; i >= 0; i--) {
-        JSLock::DropAllLocks dropAllLocks(exec);
+        APICallbackShim callbackShim(exec);
         JSObjectInitializeCallback initialize = initRoutines[i];
         initialize(toRef(exec), toRef(this));
     }
@@ -117,7 +118,7 @@ bool JSCallbackObject<Base>::getOwnPropertySlot(ExecState* exec, const Identifie
         if (JSObjectHasPropertyCallback hasProperty = jsClass->hasProperty) {
             if (!propertyNameRef)
                 propertyNameRef = OpaqueJSString::create(propertyName.ustring());
-            JSLock::DropAllLocks dropAllLocks(exec);
+            APICallbackShim callbackShim(exec);
             if (hasProperty(ctx, thisRef, propertyNameRef.get())) {
                 slot.setCustom(this, callbackGetter);
                 return true;
@@ -128,7 +129,7 @@ bool JSCallbackObject<Base>::getOwnPropertySlot(ExecState* exec, const Identifie
             JSValueRef exception = 0;
             JSValueRef value;
             {
-                JSLock::DropAllLocks dropAllLocks(exec);
+                APICallbackShim callbackShim(exec);
                 value = getProperty(ctx, thisRef, propertyNameRef.get(), &exception);
             }
             if (exception) {
@@ -167,6 +168,25 @@ bool JSCallbackObject<Base>::getOwnPropertySlot(ExecState* exec, unsigned proper
 }
 
 template <class Base>
+bool JSCallbackObject<Base>::getOwnPropertyDescriptor(ExecState* exec, const Identifier& propertyName, PropertyDescriptor& descriptor)
+{
+    PropertySlot slot;
+    if (getOwnPropertySlot(exec, propertyName, slot)) {
+        // Ideally we should return an access descriptor, but returning a value descriptor is better than nothing.
+        JSValue value = slot.getValue(exec, propertyName);
+        if (!exec->hadException())
+            descriptor.setValue(value);
+        // We don't know whether the property is configurable, but assume it is.
+        descriptor.setConfigurable(true);
+        // We don't know whether the property is enumerable (we could call getOwnPropertyNames() to find out), but assume it isn't.
+        descriptor.setEnumerable(false);
+        return true;
+    }
+
+    return Base::getOwnPropertyDescriptor(exec, propertyName, descriptor);
+}
+
+template <class Base>
 void JSCallbackObject<Base>::put(ExecState* exec, const Identifier& propertyName, JSValue value, PutPropertySlot& slot)
 {
     JSContextRef ctx = toRef(exec);
@@ -181,7 +201,7 @@ void JSCallbackObject<Base>::put(ExecState* exec, const Identifier& propertyName
             JSValueRef exception = 0;
             bool result;
             {
-                JSLock::DropAllLocks dropAllLocks(exec);
+                APICallbackShim callbackShim(exec);
                 result = setProperty(ctx, thisRef, propertyNameRef.get(), valueRef, &exception);
             }
             if (exception)
@@ -200,7 +220,7 @@ void JSCallbackObject<Base>::put(ExecState* exec, const Identifier& propertyName
                     JSValueRef exception = 0;
                     bool result;
                     {
-                        JSLock::DropAllLocks dropAllLocks(exec);
+                        APICallbackShim callbackShim(exec);
                         result = setProperty(ctx, thisRef, propertyNameRef.get(), valueRef, &exception);
                     }
                     if (exception)
@@ -239,7 +259,7 @@ bool JSCallbackObject<Base>::deleteProperty(ExecState* exec, const Identifier& p
             JSValueRef exception = 0;
             bool result;
             {
-                JSLock::DropAllLocks dropAllLocks(exec);
+                APICallbackShim callbackShim(exec);
                 result = deleteProperty(ctx, thisRef, propertyNameRef.get(), &exception);
             }
             if (exception)
@@ -301,7 +321,7 @@ JSObject* JSCallbackObject<Base>::construct(ExecState* exec, JSObject* construct
             JSValueRef exception = 0;
             JSObject* result;
             {
-                JSLock::DropAllLocks dropAllLocks(exec);
+                APICallbackShim callbackShim(exec);
                 result = toJS(callAsConstructor(execRef, constructorRef, argumentCount, arguments.data(), &exception));
             }
             if (exception)
@@ -326,7 +346,7 @@ bool JSCallbackObject<Base>::hasInstance(ExecState* exec, JSValue value, JSValue
             JSValueRef exception = 0;
             bool result;
             {
-                JSLock::DropAllLocks dropAllLocks(exec);
+                APICallbackShim callbackShim(exec);
                 result = hasInstance(execRef, thisRef, valueRef, &exception);
             }
             if (exception)
@@ -365,7 +385,7 @@ JSValue JSCallbackObject<Base>::call(ExecState* exec, JSObject* functionObject,
             JSValueRef exception = 0;
             JSValue result;
             {
-                JSLock::DropAllLocks dropAllLocks(exec);
+                APICallbackShim callbackShim(exec);
                 result = toJS(exec, callAsFunction(execRef, functionRef, thisObjRef, argumentCount, arguments.data(), &exception));
             }
             if (exception)
@@ -379,14 +399,14 @@ JSValue JSCallbackObject<Base>::call(ExecState* exec, JSObject* functionObject,
 }
 
 template <class Base>
-void JSCallbackObject<Base>::getOwnPropertyNames(ExecState* exec, PropertyNameArray& propertyNames)
+void JSCallbackObject<Base>::getOwnPropertyNames(ExecState* exec, PropertyNameArray& propertyNames, EnumerationMode mode)
 {
     JSContextRef execRef = toRef(exec);
     JSObjectRef thisRef = toRef(this);
     
     for (JSClassRef jsClass = classRef(); jsClass; jsClass = jsClass->parentClass) {
         if (JSObjectGetPropertyNamesCallback getPropertyNames = jsClass->getPropertyNames) {
-            JSLock::DropAllLocks dropAllLocks(exec);
+            APICallbackShim callbackShim(exec);
             getPropertyNames(execRef, thisRef, toRef(&propertyNames));
         }
         
@@ -396,7 +416,7 @@ void JSCallbackObject<Base>::getOwnPropertyNames(ExecState* exec, PropertyNameAr
             for (iterator it = staticValues->begin(); it != end; ++it) {
                 UString::Rep* name = it->first.get();
                 StaticValueEntry* entry = it->second;
-                if (entry->getProperty && !(entry->attributes & kJSPropertyAttributeDontEnum))
+                if (entry->getProperty && (!(entry->attributes & kJSPropertyAttributeDontEnum) || (mode == IncludeDontEnumProperties)))
                     propertyNames.add(Identifier(exec, name));
             }
         }
@@ -407,13 +427,13 @@ void JSCallbackObject<Base>::getOwnPropertyNames(ExecState* exec, PropertyNameAr
             for (iterator it = staticFunctions->begin(); it != end; ++it) {
                 UString::Rep* name = it->first.get();
                 StaticFunctionEntry* entry = it->second;
-                if (!(entry->attributes & kJSPropertyAttributeDontEnum))
+                if (!(entry->attributes & kJSPropertyAttributeDontEnum) || (mode == IncludeDontEnumProperties))
                     propertyNames.add(Identifier(exec, name));
             }
         }
     }
     
-    Base::getOwnPropertyNames(exec, propertyNames);
+    Base::getOwnPropertyNames(exec, propertyNames, mode);
 }
 
 template <class Base>
@@ -432,7 +452,7 @@ double JSCallbackObject<Base>::toNumber(ExecState* exec) const
             JSValueRef exception = 0;
             JSValueRef value;
             {
-                JSLock::DropAllLocks dropAllLocks(exec);
+                APICallbackShim callbackShim(exec);
                 value = convertToType(ctx, thisRef, kJSTypeNumber, &exception);
             }
             if (exception) {
@@ -459,7 +479,7 @@ UString JSCallbackObject<Base>::toString(ExecState* exec) const
             JSValueRef exception = 0;
             JSValueRef value;
             {
-                JSLock::DropAllLocks dropAllLocks(exec);
+                APICallbackShim callbackShim(exec);
                 value = convertToType(ctx, thisRef, kJSTypeString, &exception);
             }
             if (exception) {
@@ -512,7 +532,7 @@ JSValue JSCallbackObject<Base>::staticValueGetter(ExecState* exec, const Identif
                     JSValueRef exception = 0;
                     JSValueRef value;
                     {
-                        JSLock::DropAllLocks dropAllLocks(exec);
+                        APICallbackShim callbackShim(exec);
                         value = getProperty(toRef(exec), thisRef, propertyNameRef.get(), &exception);
                     }
                     if (exception) {
@@ -566,7 +586,7 @@ JSValue JSCallbackObject<Base>::callbackGetter(ExecState* exec, const Identifier
             JSValueRef exception = 0;
             JSValueRef value;
             {
-                JSLock::DropAllLocks dropAllLocks(exec);
+                APICallbackShim callbackShim(exec);
                 value = getProperty(toRef(exec), thisRef, propertyNameRef.get(), &exception);
             }
             if (exception) {
diff --git a/JavaScriptCore/API/JSClassRef.cpp b/JavaScriptCore/API/JSClassRef.cpp
index afde7ce..c6685bf 100644
--- a/JavaScriptCore/API/JSClassRef.cpp
+++ b/JavaScriptCore/API/JSClassRef.cpp
@@ -34,6 +34,7 @@
 #include <runtime/ObjectPrototype.h>
 #include <runtime/Identifier.h>
 
+using namespace std;
 using namespace JSC;
 
 const JSClassDefinition kJSClassDefinitionEmpty = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
@@ -52,7 +53,7 @@ OpaqueJSClass::OpaqueJSClass(const JSClassDefinition* definition, OpaqueJSClass*
     , callAsConstructor(definition->callAsConstructor)
     , hasInstance(definition->hasInstance)
     , convertToType(definition->convertToType)
-    , m_className(UString::Rep::createFromUTF8(definition->className))
+    , m_className(UString::createFromUTF8(definition->className).rep()->ref())
     , m_staticValues(0)
     , m_staticFunctions(0)
 {
@@ -61,8 +62,9 @@ OpaqueJSClass::OpaqueJSClass(const JSClassDefinition* definition, OpaqueJSClass*
     if (const JSStaticValue* staticValue = definition->staticValues) {
         m_staticValues = new OpaqueJSClassStaticValuesTable();
         while (staticValue->name) {
-            m_staticValues->add(UString::Rep::createFromUTF8(staticValue->name),
-                              new StaticValueEntry(staticValue->getProperty, staticValue->setProperty, staticValue->attributes));
+            // Use a local variable here to sidestep an RVCT compiler bug.
+            StaticValueEntry* entry = new StaticValueEntry(staticValue->getProperty, staticValue->setProperty, staticValue->attributes);
+            m_staticValues->add(UString::createFromUTF8(staticValue->name).rep()->ref(), entry);
             ++staticValue;
         }
     }
@@ -70,8 +72,9 @@ OpaqueJSClass::OpaqueJSClass(const JSClassDefinition* definition, OpaqueJSClass*
     if (const JSStaticFunction* staticFunction = definition->staticFunctions) {
         m_staticFunctions = new OpaqueJSClassStaticFunctionsTable();
         while (staticFunction->name) {
-            m_staticFunctions->add(UString::Rep::createFromUTF8(staticFunction->name),
-                                 new StaticFunctionEntry(staticFunction->callAsFunction, staticFunction->attributes));
+            // Use a local variable here to sidestep an RVCT compiler bug.
+            StaticFunctionEntry* entry = new StaticFunctionEntry(staticFunction->callAsFunction, staticFunction->attributes);
+            m_staticFunctions->add(UString::createFromUTF8(staticFunction->name).rep()->ref(), entry);
             ++staticFunction;
         }
     }
@@ -82,12 +85,12 @@ OpaqueJSClass::OpaqueJSClass(const JSClassDefinition* definition, OpaqueJSClass*
 
 OpaqueJSClass::~OpaqueJSClass()
 {
-    ASSERT(!m_className.rep()->identifierTable());
+    ASSERT(!m_className.rep()->isIdentifier());
 
     if (m_staticValues) {
         OpaqueJSClassStaticValuesTable::const_iterator end = m_staticValues->end();
         for (OpaqueJSClassStaticValuesTable::const_iterator it = m_staticValues->begin(); it != end; ++it) {
-            ASSERT(!it->first->identifierTable());
+            ASSERT(!it->first->isIdentifier());
             delete it->second;
         }
         delete m_staticValues;
@@ -96,7 +99,7 @@ OpaqueJSClass::~OpaqueJSClass()
     if (m_staticFunctions) {
         OpaqueJSClassStaticFunctionsTable::const_iterator end = m_staticFunctions->end();
         for (OpaqueJSClassStaticFunctionsTable::const_iterator it = m_staticFunctions->begin(); it != end; ++it) {
-            ASSERT(!it->first->identifierTable());
+            ASSERT(!it->first->isIdentifier());
             delete it->second;
         }
         delete m_staticFunctions;
@@ -118,39 +121,32 @@ static void clearReferenceToPrototype(JSObjectRef prototype)
     jsClassData->cachedPrototype = 0;
 }
 
-PassRefPtr<OpaqueJSClass> OpaqueJSClass::create(const JSClassDefinition* definition)
+PassRefPtr<OpaqueJSClass> OpaqueJSClass::create(const JSClassDefinition* clientDefinition)
 {
-    if (const JSStaticFunction* staticFunctions = definition->staticFunctions) {
-        // copy functions into a prototype class
-        JSClassDefinition protoDefinition = kJSClassDefinitionEmpty;
-        protoDefinition.staticFunctions = staticFunctions;
-        protoDefinition.finalize = clearReferenceToPrototype;
-        
-        // We are supposed to use JSClassRetain/Release but since we know that we currently have
-        // the only reference to this class object we cheat and use a RefPtr instead.
-        RefPtr<OpaqueJSClass> protoClass = adoptRef(new OpaqueJSClass(&protoDefinition, 0));
-
-        // remove functions from the original class
-        JSClassDefinition objectDefinition = *definition;
-        objectDefinition.staticFunctions = 0;
-
-        return adoptRef(new OpaqueJSClass(&objectDefinition, protoClass.get()));
-    }
+    JSClassDefinition definition = *clientDefinition; // Avoid modifying client copy.
 
-    return adoptRef(new OpaqueJSClass(definition, 0));
+    JSClassDefinition protoDefinition = kJSClassDefinitionEmpty;
+    protoDefinition.finalize = clearReferenceToPrototype;
+    swap(definition.staticFunctions, protoDefinition.staticFunctions); // Move static functions to the prototype.
+    
+    // We are supposed to use JSClassRetain/Release but since we know that we currently have
+    // the only reference to this class object we cheat and use a RefPtr instead.
+    RefPtr<OpaqueJSClass> protoClass = adoptRef(new OpaqueJSClass(&protoDefinition, 0));
+    return adoptRef(new OpaqueJSClass(&definition, protoClass.get()));
 }
 
 OpaqueJSClassContextData::OpaqueJSClassContextData(OpaqueJSClass* jsClass)
     : m_class(jsClass)
-    , cachedPrototype(0)
 {
     if (jsClass->m_staticValues) {
         staticValues = new OpaqueJSClassStaticValuesTable;
         OpaqueJSClassStaticValuesTable::const_iterator end = jsClass->m_staticValues->end();
         for (OpaqueJSClassStaticValuesTable::const_iterator it = jsClass->m_staticValues->begin(); it != end; ++it) {
-            ASSERT(!it->first->identifierTable());
-            staticValues->add(UString::Rep::createCopying(it->first->data(), it->first->size()),
-                              new StaticValueEntry(it->second->getProperty, it->second->setProperty, it->second->attributes));
+            ASSERT(!it->first->isIdentifier());
+            // Use a local variable here to sidestep an RVCT compiler bug.
+            StaticValueEntry* entry = new StaticValueEntry(it->second->getProperty, it->second->setProperty, it->second->attributes);
+            staticValues->add(UString::Rep::create(it->first->data(), it->first->size()), entry);
+
         }
             
     } else
@@ -161,9 +157,10 @@ OpaqueJSClassContextData::OpaqueJSClassContextData(OpaqueJSClass* jsClass)
         staticFunctions = new OpaqueJSClassStaticFunctionsTable;
         OpaqueJSClassStaticFunctionsTable::const_iterator end = jsClass->m_staticFunctions->end();
         for (OpaqueJSClassStaticFunctionsTable::const_iterator it = jsClass->m_staticFunctions->begin(); it != end; ++it) {
-            ASSERT(!it->first->identifierTable());
-            staticFunctions->add(UString::Rep::createCopying(it->first->data(), it->first->size()),
-                              new StaticFunctionEntry(it->second->callAsFunction, it->second->attributes));
+            ASSERT(!it->first->isIdentifier());
+            // Use a local variable here to sidestep an RVCT compiler bug.
+            StaticFunctionEntry* entry = new StaticFunctionEntry(it->second->callAsFunction, it->second->attributes);
+            staticFunctions->add(UString::Rep::create(it->first->data(), it->first->size()), entry);
         }
             
     } else
@@ -240,5 +237,5 @@ JSObject* OpaqueJSClass::prototype(ExecState* exec)
                 jsClassData.cachedPrototype->setPrototype(prototype);
         }
     }
-    return jsClassData.cachedPrototype;
+    return jsClassData.cachedPrototype.get();
 }
diff --git a/JavaScriptCore/API/JSClassRef.h b/JavaScriptCore/API/JSClassRef.h
index c4777dd..ae60aad 100644
--- a/JavaScriptCore/API/JSClassRef.h
+++ b/JavaScriptCore/API/JSClassRef.h
@@ -31,6 +31,7 @@
 #include <runtime/JSObject.h>
 #include <runtime/Protect.h>
 #include <runtime/UString.h>
+#include <runtime/WeakGCPtr.h>
 #include <wtf/HashMap.h>
 #include <wtf/RefCounted.h>
 
@@ -76,7 +77,7 @@ struct OpaqueJSClassContextData : Noncopyable {
 
     OpaqueJSClassStaticValuesTable* staticValues;
     OpaqueJSClassStaticFunctionsTable* staticFunctions;
-    JSC::JSObject* cachedPrototype;
+    JSC::WeakGCPtr<JSC::JSObject> cachedPrototype;
 };
 
 struct OpaqueJSClass : public ThreadSafeShared<OpaqueJSClass> {
diff --git a/JavaScriptCore/API/JSContextRef.cpp b/JavaScriptCore/API/JSContextRef.cpp
index e6626b7..6bdc3c8 100644
--- a/JavaScriptCore/API/JSContextRef.cpp
+++ b/JavaScriptCore/API/JSContextRef.cpp
@@ -35,7 +35,7 @@
 #include "JSObject.h"
 #include <wtf/Platform.h>
 
-#if PLATFORM(DARWIN)
+#if OS(DARWIN)
 #include <mach-o/dyld.h>
 
 static const int32_t webkitFirstVersionWithConcurrentGlobalContexts = 0x2100500; // 528.5.0
@@ -46,7 +46,7 @@ using namespace JSC;
 JSContextGroupRef JSContextGroupCreate()
 {
     initializeThreading();
-    return toRef(JSGlobalData::create().releaseRef());
+    return toRef(JSGlobalData::createNonDefault().releaseRef());
 }
 
 JSContextGroupRef JSContextGroupRetain(JSContextGroupRef group)
@@ -63,7 +63,7 @@ void JSContextGroupRelease(JSContextGroupRef group)
 JSGlobalContextRef JSGlobalContextCreate(JSClassRef globalObjectClass)
 {
     initializeThreading();
-#if PLATFORM(DARWIN)
+#if OS(DARWIN)
     // When running on Tiger or Leopard, or if the application was linked before JSGlobalContextCreate was changed
     // to use a unique JSGlobalData, we use a shared one for compatibility.
 #if !defined(BUILDING_ON_TIGER) && !defined(BUILDING_ON_LEOPARD)
@@ -74,7 +74,7 @@ JSGlobalContextRef JSGlobalContextCreate(JSClassRef globalObjectClass)
         JSLock lock(LockForReal);
         return JSGlobalContextCreateInGroup(toRef(&JSGlobalData::sharedInstance()), globalObjectClass);
     }
-#endif // PLATFORM(DARWIN)
+#endif // OS(DARWIN)
 
     return JSGlobalContextCreateInGroup(0, globalObjectClass);
 }
@@ -84,8 +84,9 @@ JSGlobalContextRef JSGlobalContextCreateInGroup(JSContextGroupRef group, JSClass
     initializeThreading();
 
     JSLock lock(LockForReal);
+    RefPtr<JSGlobalData> globalData = group ? PassRefPtr<JSGlobalData>(toJS(group)) : JSGlobalData::createNonDefault();
 
-    RefPtr<JSGlobalData> globalData = group ? PassRefPtr<JSGlobalData>(toJS(group)) : JSGlobalData::create();
+    APIEntryShim entryShim(globalData.get(), false);
 
 #if ENABLE(JSC_MULTIPLE_THREADS)
     globalData->makeUsableFromMultipleThreads();
@@ -108,12 +109,9 @@ JSGlobalContextRef JSGlobalContextCreateInGroup(JSContextGroupRef group, JSClass
 JSGlobalContextRef JSGlobalContextRetain(JSGlobalContextRef ctx)
 {
     ExecState* exec = toJS(ctx);
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSGlobalData& globalData = exec->globalData();
-
-    globalData.heap.registerThread();
-
     gcProtect(exec->dynamicGlobalObject());
     globalData.ref();
     return ctx;
@@ -122,18 +120,16 @@ JSGlobalContextRef JSGlobalContextRetain(JSGlobalContextRef ctx)
 void JSGlobalContextRelease(JSGlobalContextRef ctx)
 {
     ExecState* exec = toJS(ctx);
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec, false);
 
     gcUnprotect(exec->dynamicGlobalObject());
 
     JSGlobalData& globalData = exec->globalData();
     if (globalData.refCount() == 2) { // One reference is held by JSGlobalObject, another added by JSGlobalContextRetain().
         // The last reference was released, this is our last chance to collect.
-        ASSERT(!globalData.heap.protectedObjectCount());
-        ASSERT(!globalData.heap.isBusy());
         globalData.heap.destroy();
     } else
-        globalData.heap.collect();
+        globalData.heap.collectAllGarbage();
 
     globalData.deref();
 }
@@ -141,8 +137,7 @@ void JSGlobalContextRelease(JSGlobalContextRef ctx)
 JSObjectRef JSContextGetGlobalObject(JSContextRef ctx)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     // It is necessary to call toThisObject to get the wrapper object when used with WebCore.
     return toRef(exec->lexicalGlobalObject()->toThisObject(exec));
@@ -157,8 +152,7 @@ JSContextGroupRef JSContextGetGroup(JSContextRef ctx)
 JSGlobalContextRef JSContextGetGlobalContext(JSContextRef ctx)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     return toGlobalRef(exec->lexicalGlobalObject()->globalExec());
 }
diff --git a/JavaScriptCore/API/JSObjectRef.cpp b/JavaScriptCore/API/JSObjectRef.cpp
index 06ef578..faaa4eb 100644
--- a/JavaScriptCore/API/JSObjectRef.cpp
+++ b/JavaScriptCore/API/JSObjectRef.cpp
@@ -76,8 +76,7 @@ void JSClassRelease(JSClassRef jsClass)
 JSObjectRef JSObjectMake(JSContextRef ctx, JSClassRef jsClass, void* data)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     if (!jsClass)
         return toRef(new (exec) JSObject(exec->lexicalGlobalObject()->emptyObjectStructure())); // slightly more efficient
@@ -92,8 +91,7 @@ JSObjectRef JSObjectMake(JSContextRef ctx, JSClassRef jsClass, void* data)
 JSObjectRef JSObjectMakeFunctionWithCallback(JSContextRef ctx, JSStringRef name, JSObjectCallAsFunctionCallback callAsFunction)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     Identifier nameID = name ? name->identifier(&exec->globalData()) : Identifier(exec, "anonymous");
     
@@ -103,8 +101,7 @@ JSObjectRef JSObjectMakeFunctionWithCallback(JSContextRef ctx, JSStringRef name,
 JSObjectRef JSObjectMakeConstructor(JSContextRef ctx, JSClassRef jsClass, JSObjectCallAsConstructorCallback callAsConstructor)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSValue jsPrototype = jsClass ? jsClass->prototype(exec) : 0;
     if (!jsPrototype)
@@ -118,8 +115,7 @@ JSObjectRef JSObjectMakeConstructor(JSContextRef ctx, JSClassRef jsClass, JSObje
 JSObjectRef JSObjectMakeFunction(JSContextRef ctx, JSStringRef name, unsigned parameterCount, const JSStringRef parameterNames[], JSStringRef body, JSStringRef sourceURL, int startingLineNumber, JSValueRef* exception)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     Identifier nameID = name ? name->identifier(&exec->globalData()) : Identifier(exec, "anonymous");
     
@@ -141,8 +137,7 @@ JSObjectRef JSObjectMakeFunction(JSContextRef ctx, JSStringRef name, unsigned pa
 JSObjectRef JSObjectMakeArray(JSContextRef ctx, size_t argumentCount, const JSValueRef arguments[],  JSValueRef* exception)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSObject* result;
     if (argumentCount) {
@@ -167,8 +162,7 @@ JSObjectRef JSObjectMakeArray(JSContextRef ctx, size_t argumentCount, const JSVa
 JSObjectRef JSObjectMakeDate(JSContextRef ctx, size_t argumentCount, const JSValueRef arguments[],  JSValueRef* exception)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     MarkedArgumentBuffer argList;
     for (size_t i = 0; i < argumentCount; ++i)
@@ -188,8 +182,7 @@ JSObjectRef JSObjectMakeDate(JSContextRef ctx, size_t argumentCount, const JSVal
 JSObjectRef JSObjectMakeError(JSContextRef ctx, size_t argumentCount, const JSValueRef arguments[],  JSValueRef* exception)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     MarkedArgumentBuffer argList;
     for (size_t i = 0; i < argumentCount; ++i)
@@ -209,8 +202,7 @@ JSObjectRef JSObjectMakeError(JSContextRef ctx, size_t argumentCount, const JSVa
 JSObjectRef JSObjectMakeRegExp(JSContextRef ctx, size_t argumentCount, const JSValueRef arguments[],  JSValueRef* exception)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     MarkedArgumentBuffer argList;
     for (size_t i = 0; i < argumentCount; ++i)
@@ -230,8 +222,7 @@ JSObjectRef JSObjectMakeRegExp(JSContextRef ctx, size_t argumentCount, const JSV
 JSValueRef JSObjectGetPrototype(JSContextRef ctx, JSObjectRef object)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSObject* jsObject = toJS(object);
     return toRef(exec, jsObject->prototype());
@@ -240,8 +231,7 @@ JSValueRef JSObjectGetPrototype(JSContextRef ctx, JSObjectRef object)
 void JSObjectSetPrototype(JSContextRef ctx, JSObjectRef object, JSValueRef value)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSObject* jsObject = toJS(object);
     JSValue jsValue = toJS(exec, value);
@@ -252,8 +242,7 @@ void JSObjectSetPrototype(JSContextRef ctx, JSObjectRef object, JSValueRef value
 bool JSObjectHasProperty(JSContextRef ctx, JSObjectRef object, JSStringRef propertyName)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSObject* jsObject = toJS(object);
     
@@ -263,8 +252,7 @@ bool JSObjectHasProperty(JSContextRef ctx, JSObjectRef object, JSStringRef prope
 JSValueRef JSObjectGetProperty(JSContextRef ctx, JSObjectRef object, JSStringRef propertyName, JSValueRef* exception)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSObject* jsObject = toJS(object);
 
@@ -280,8 +268,7 @@ JSValueRef JSObjectGetProperty(JSContextRef ctx, JSObjectRef object, JSStringRef
 void JSObjectSetProperty(JSContextRef ctx, JSObjectRef object, JSStringRef propertyName, JSValueRef value, JSPropertyAttributes attributes, JSValueRef* exception)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSObject* jsObject = toJS(object);
     Identifier name(propertyName->identifier(&exec->globalData()));
@@ -304,8 +291,7 @@ void JSObjectSetProperty(JSContextRef ctx, JSObjectRef object, JSStringRef prope
 JSValueRef JSObjectGetPropertyAtIndex(JSContextRef ctx, JSObjectRef object, unsigned propertyIndex, JSValueRef* exception)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSObject* jsObject = toJS(object);
 
@@ -322,8 +308,7 @@ JSValueRef JSObjectGetPropertyAtIndex(JSContextRef ctx, JSObjectRef object, unsi
 void JSObjectSetPropertyAtIndex(JSContextRef ctx, JSObjectRef object, unsigned propertyIndex, JSValueRef value, JSValueRef* exception)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSObject* jsObject = toJS(object);
     JSValue jsValue = toJS(exec, value);
@@ -339,8 +324,7 @@ void JSObjectSetPropertyAtIndex(JSContextRef ctx, JSObjectRef object, unsigned p
 bool JSObjectDeleteProperty(JSContextRef ctx, JSObjectRef object, JSStringRef propertyName, JSValueRef* exception)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSObject* jsObject = toJS(object);
 
@@ -389,8 +373,7 @@ bool JSObjectIsFunction(JSContextRef, JSObjectRef object)
 JSValueRef JSObjectCallAsFunction(JSContextRef ctx, JSObjectRef object, JSObjectRef thisObject, size_t argumentCount, const JSValueRef arguments[], JSValueRef* exception)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSObject* jsObject = toJS(object);
     JSObject* jsThisObject = toJS(thisObject);
@@ -427,8 +410,7 @@ bool JSObjectIsConstructor(JSContextRef, JSObjectRef object)
 JSObjectRef JSObjectCallAsConstructor(JSContextRef ctx, JSObjectRef object, size_t argumentCount, const JSValueRef arguments[], JSValueRef* exception)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSObject* jsObject = toJS(object);
 
@@ -466,8 +448,7 @@ JSPropertyNameArrayRef JSObjectCopyPropertyNames(JSContextRef ctx, JSObjectRef o
 {
     JSObject* jsObject = toJS(object);
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSGlobalData* globalData = &exec->globalData();
 
@@ -492,7 +473,7 @@ JSPropertyNameArrayRef JSPropertyNameArrayRetain(JSPropertyNameArrayRef array)
 void JSPropertyNameArrayRelease(JSPropertyNameArrayRef array)
 {
     if (--array->refCount == 0) {
-        JSLock lock(array->globalData->isSharedInstance ? LockForReal : SilenceAssertionsOnly);
+        APIEntryShim entryShim(array->globalData, false);
         delete array;
     }
 }
@@ -510,9 +491,6 @@ JSStringRef JSPropertyNameArrayGetNameAtIndex(JSPropertyNameArrayRef array, size
 void JSPropertyNameAccumulatorAddName(JSPropertyNameAccumulatorRef array, JSStringRef propertyName)
 {
     PropertyNameArray* propertyNames = toJS(array);
-
-    propertyNames->globalData()->heap.registerThread();
-    JSLock lock(propertyNames->globalData()->isSharedInstance ? LockForReal : SilenceAssertionsOnly);
-
+    APIEntryShim entryShim(propertyNames->globalData());
     propertyNames->add(propertyName->identifier(propertyNames->globalData()));
 }
diff --git a/JavaScriptCore/API/JSValueRef.cpp b/JavaScriptCore/API/JSValueRef.cpp
index 31859d6..a12cc34 100644
--- a/JavaScriptCore/API/JSValueRef.cpp
+++ b/JavaScriptCore/API/JSValueRef.cpp
@@ -28,6 +28,7 @@
 
 #include <wtf/Platform.h>
 #include "APICast.h"
+#include "APIShims.h"
 #include "JSCallbackObject.h"
 
 #include <runtime/JSGlobalObject.h>
@@ -41,13 +42,14 @@
 
 #include <algorithm> // for std::min
 
-JSType JSValueGetType(JSContextRef ctx, JSValueRef value)
+using namespace JSC;
+
+::JSType JSValueGetType(JSContextRef ctx, JSValueRef value)
 {
-    JSC::ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSC::JSLock lock(exec);
+    ExecState* exec = toJS(ctx);
+    APIEntryShim entryShim(exec);
 
-    JSC::JSValue jsValue = toJS(exec, value);
+    JSValue jsValue = toJS(exec, value);
 
     if (jsValue.isUndefined())
         return kJSTypeUndefined;
@@ -63,13 +65,10 @@ JSType JSValueGetType(JSContextRef ctx, JSValueRef value)
     return kJSTypeObject;
 }
 
-using namespace JSC; // placed here to avoid conflict between JSC::JSType and JSType, above.
-
 bool JSValueIsUndefined(JSContextRef ctx, JSValueRef value)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSValue jsValue = toJS(exec, value);
     return jsValue.isUndefined();
@@ -78,8 +77,7 @@ bool JSValueIsUndefined(JSContextRef ctx, JSValueRef value)
 bool JSValueIsNull(JSContextRef ctx, JSValueRef value)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSValue jsValue = toJS(exec, value);
     return jsValue.isNull();
@@ -88,8 +86,7 @@ bool JSValueIsNull(JSContextRef ctx, JSValueRef value)
 bool JSValueIsBoolean(JSContextRef ctx, JSValueRef value)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSValue jsValue = toJS(exec, value);
     return jsValue.isBoolean();
@@ -98,8 +95,7 @@ bool JSValueIsBoolean(JSContextRef ctx, JSValueRef value)
 bool JSValueIsNumber(JSContextRef ctx, JSValueRef value)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSValue jsValue = toJS(exec, value);
     return jsValue.isNumber();
@@ -108,8 +104,7 @@ bool JSValueIsNumber(JSContextRef ctx, JSValueRef value)
 bool JSValueIsString(JSContextRef ctx, JSValueRef value)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSValue jsValue = toJS(exec, value);
     return jsValue.isString();
@@ -118,8 +113,7 @@ bool JSValueIsString(JSContextRef ctx, JSValueRef value)
 bool JSValueIsObject(JSContextRef ctx, JSValueRef value)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSValue jsValue = toJS(exec, value);
     return jsValue.isObject();
@@ -128,8 +122,7 @@ bool JSValueIsObject(JSContextRef ctx, JSValueRef value)
 bool JSValueIsObjectOfClass(JSContextRef ctx, JSValueRef value, JSClassRef jsClass)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSValue jsValue = toJS(exec, value);
     
@@ -145,8 +138,7 @@ bool JSValueIsObjectOfClass(JSContextRef ctx, JSValueRef value, JSClassRef jsCla
 bool JSValueIsEqual(JSContextRef ctx, JSValueRef a, JSValueRef b, JSValueRef* exception)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSValue jsA = toJS(exec, a);
     JSValue jsB = toJS(exec, b);
@@ -163,8 +155,7 @@ bool JSValueIsEqual(JSContextRef ctx, JSValueRef a, JSValueRef b, JSValueRef* ex
 bool JSValueIsStrictEqual(JSContextRef ctx, JSValueRef a, JSValueRef b)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSValue jsA = toJS(exec, a);
     JSValue jsB = toJS(exec, b);
@@ -175,8 +166,7 @@ bool JSValueIsStrictEqual(JSContextRef ctx, JSValueRef a, JSValueRef b)
 bool JSValueIsInstanceOfConstructor(JSContextRef ctx, JSValueRef value, JSObjectRef constructor, JSValueRef* exception)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSValue jsValue = toJS(exec, value);
 
@@ -195,8 +185,7 @@ bool JSValueIsInstanceOfConstructor(JSContextRef ctx, JSValueRef value, JSObject
 JSValueRef JSValueMakeUndefined(JSContextRef ctx)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     return toRef(exec, jsUndefined());
 }
@@ -204,8 +193,7 @@ JSValueRef JSValueMakeUndefined(JSContextRef ctx)
 JSValueRef JSValueMakeNull(JSContextRef ctx)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     return toRef(exec, jsNull());
 }
@@ -213,8 +201,7 @@ JSValueRef JSValueMakeNull(JSContextRef ctx)
 JSValueRef JSValueMakeBoolean(JSContextRef ctx, bool value)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     return toRef(exec, jsBoolean(value));
 }
@@ -222,8 +209,7 @@ JSValueRef JSValueMakeBoolean(JSContextRef ctx, bool value)
 JSValueRef JSValueMakeNumber(JSContextRef ctx, double value)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     return toRef(exec, jsNumber(exec, value));
 }
@@ -231,8 +217,7 @@ JSValueRef JSValueMakeNumber(JSContextRef ctx, double value)
 JSValueRef JSValueMakeString(JSContextRef ctx, JSStringRef string)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     return toRef(exec, jsString(exec, string->ustring()));
 }
@@ -240,8 +225,7 @@ JSValueRef JSValueMakeString(JSContextRef ctx, JSStringRef string)
 bool JSValueToBoolean(JSContextRef ctx, JSValueRef value)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSValue jsValue = toJS(exec, value);
     return jsValue.toBoolean(exec);
@@ -250,8 +234,7 @@ bool JSValueToBoolean(JSContextRef ctx, JSValueRef value)
 double JSValueToNumber(JSContextRef ctx, JSValueRef value, JSValueRef* exception)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSValue jsValue = toJS(exec, value);
 
@@ -268,8 +251,7 @@ double JSValueToNumber(JSContextRef ctx, JSValueRef value, JSValueRef* exception
 JSStringRef JSValueToStringCopy(JSContextRef ctx, JSValueRef value, JSValueRef* exception)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSValue jsValue = toJS(exec, value);
     
@@ -286,8 +268,7 @@ JSStringRef JSValueToStringCopy(JSContextRef ctx, JSValueRef value, JSValueRef*
 JSObjectRef JSValueToObject(JSContextRef ctx, JSValueRef value, JSValueRef* exception)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSValue jsValue = toJS(exec, value);
     
@@ -304,8 +285,7 @@ JSObjectRef JSValueToObject(JSContextRef ctx, JSValueRef value, JSValueRef* exce
 void JSValueProtect(JSContextRef ctx, JSValueRef value)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSValue jsValue = toJSForGC(exec, value);
     gcProtect(jsValue);
@@ -314,8 +294,7 @@ void JSValueProtect(JSContextRef ctx, JSValueRef value)
 void JSValueUnprotect(JSContextRef ctx, JSValueRef value)
 {
     ExecState* exec = toJS(ctx);
-    exec->globalData().heap.registerThread();
-    JSLock lock(exec);
+    APIEntryShim entryShim(exec);
 
     JSValue jsValue = toJSForGC(exec, value);
     gcUnprotect(jsValue);
diff --git a/JavaScriptCore/API/OpaqueJSString.cpp b/JavaScriptCore/API/OpaqueJSString.cpp
index 7c7b1af..f740abe 100644
--- a/JavaScriptCore/API/OpaqueJSString.cpp
+++ b/JavaScriptCore/API/OpaqueJSString.cpp
@@ -42,7 +42,7 @@ PassRefPtr<OpaqueJSString> OpaqueJSString::create(const UString& ustring)
 UString OpaqueJSString::ustring() const
 {
     if (this && m_characters)
-        return UString(m_characters, m_length, true);
+        return UString(m_characters, m_length);
     return UString::null();
 }
 
diff --git a/JavaScriptCore/API/tests/testapi.c b/JavaScriptCore/API/tests/testapi.c
index e7aba0f..ebc0cfb 100644
--- a/JavaScriptCore/API/tests/testapi.c
+++ b/JavaScriptCore/API/tests/testapi.c
@@ -623,6 +623,17 @@ static JSClassRef Derived_class(JSContextRef context)
     return jsClass;
 }
 
+static JSClassRef Derived2_class(JSContextRef context)
+{
+    static JSClassRef jsClass;
+    if (!jsClass) {
+        JSClassDefinition definition = kJSClassDefinitionEmpty;
+        definition.parentClass = Derived_class(context);
+        jsClass = JSClassCreate(&definition);
+    }
+    return jsClass;
+}
+
 static JSValueRef print_callAsFunction(JSContextRef ctx, JSObjectRef functionObject, JSObjectRef thisObject, size_t argumentCount, const JSValueRef arguments[], JSValueRef* exception)
 {
     UNUSED_PARAM(functionObject);
@@ -1070,11 +1081,21 @@ int main(int argc, char* argv[])
     ASSERT(!JSObjectSetPrivate(myConstructor, (void*)1));
     ASSERT(!JSObjectGetPrivate(myConstructor));
     
+    string = JSStringCreateWithUTF8CString("Base");
+    JSObjectRef baseConstructor = JSObjectMakeConstructor(context, Base_class(context), NULL);
+    JSObjectSetProperty(context, globalObject, string, baseConstructor, kJSPropertyAttributeNone, NULL);
+    JSStringRelease(string);
+    
     string = JSStringCreateWithUTF8CString("Derived");
     JSObjectRef derivedConstructor = JSObjectMakeConstructor(context, Derived_class(context), NULL);
     JSObjectSetProperty(context, globalObject, string, derivedConstructor, kJSPropertyAttributeNone, NULL);
     JSStringRelease(string);
     
+    string = JSStringCreateWithUTF8CString("Derived2");
+    JSObjectRef derived2Constructor = JSObjectMakeConstructor(context, Derived2_class(context), NULL);
+    JSObjectSetProperty(context, globalObject, string, derived2Constructor, kJSPropertyAttributeNone, NULL);
+    JSStringRelease(string);
+
     o = JSObjectMake(context, NULL, NULL);
     JSObjectSetProperty(context, o, jsOneIString, JSValueMakeNumber(context, 1), kJSPropertyAttributeNone, NULL);
     JSObjectSetProperty(context, o, jsCFIString,  JSValueMakeNumber(context, 1), kJSPropertyAttributeDontEnum, NULL);
@@ -1173,7 +1194,7 @@ int main(int argc, char* argv[])
     } else {
         script = JSStringCreateWithUTF8CString(scriptUTF8);
         result = JSEvaluateScript(context, script, NULL, NULL, 1, &exception);
-        if (JSValueIsUndefined(context, result))
+        if (result && JSValueIsUndefined(context, result))
             printf("PASS: Test script executed successfully.\n");
         else {
             printf("FAIL: Test script returned unexpected value:\n");
diff --git a/JavaScriptCore/API/tests/testapi.js b/JavaScriptCore/API/tests/testapi.js
index 82756b5..15c9e50 100644
--- a/JavaScriptCore/API/tests/testapi.js
+++ b/JavaScriptCore/API/tests/testapi.js
@@ -113,6 +113,35 @@ if (foundRegularType)
 else
     fail("MyObject.regularType was not enumerated");
 
+var alwaysOneDescriptor = Object.getOwnPropertyDescriptor(MyObject, "alwaysOne");
+shouldBe('typeof alwaysOneDescriptor', "object");
+shouldBe('alwaysOneDescriptor.value', MyObject.alwaysOne);
+shouldBe('alwaysOneDescriptor.configurable', true);
+shouldBe('alwaysOneDescriptor.enumerable', false); // Actually it is.
+var cantFindDescriptor = Object.getOwnPropertyDescriptor(MyObject, "cantFind");
+shouldBe('typeof cantFindDescriptor', "object");
+shouldBe('cantFindDescriptor.value', MyObject.cantFind);
+shouldBe('cantFindDescriptor.configurable', true);
+shouldBe('cantFindDescriptor.enumerable', false);
+try {
+    // If getOwnPropertyDescriptor() returned an access descriptor, this wouldn't throw.
+    Object.getOwnPropertyDescriptor(MyObject, "throwOnGet");
+} catch (e) {
+    pass("getting property descriptor of throwOnGet threw exception");
+}
+var myPropertyNameDescriptor = Object.getOwnPropertyDescriptor(MyObject, "myPropertyName");
+shouldBe('typeof myPropertyNameDescriptor', "object");
+shouldBe('myPropertyNameDescriptor.value', MyObject.myPropertyName);
+shouldBe('myPropertyNameDescriptor.configurable', true);
+shouldBe('myPropertyNameDescriptor.enumerable', false); // Actually it is.
+try {
+    // if getOwnPropertyDescriptor() returned an access descriptor, this wouldn't throw.
+    Object.getOwnPropertyDescriptor(MyObject, "hasPropertyLie");
+} catch (e) {
+    pass("getting property descriptor of hasPropertyLie threw exception");
+}
+shouldBe('Object.getOwnPropertyDescriptor(MyObject, "doesNotExist")', undefined);
+
 myObject = new MyObject();
 
 shouldBe("delete MyObject.regularType", true);
@@ -140,6 +169,9 @@ shouldThrow("MyObject.hasPropertyLie");
 
 derived = new Derived();
 
+shouldBe("derived instanceof Derived", true);
+shouldBe("derived instanceof Base", true);
+
 // base properties and functions return 1 when called/gotten; derived, 2
 shouldBe("derived.baseProtoDup()", 2);
 shouldBe("derived.baseProto()", 1);
@@ -155,6 +187,51 @@ shouldBe("derived.baseOnly = 0", 1);
 shouldBe("derived.derivedOnly = 0", 2)
 shouldBe("derived.protoDup = 0", 2);
 
+derived2 = new Derived2();
+
+shouldBe("derived2 instanceof Derived2", true);
+shouldBe("derived2 instanceof Derived", true);
+shouldBe("derived2 instanceof Base", true);
+
+// base properties and functions return 1 when called/gotten; derived, 2
+shouldBe("derived2.baseProtoDup()", 2);
+shouldBe("derived2.baseProto()", 1);
+shouldBe("derived2.baseDup", 2);
+shouldBe("derived2.baseOnly", 1);
+shouldBe("derived2.protoOnly()", 2);
+shouldBe("derived2.protoDup", 2);
+shouldBe("derived2.derivedOnly", 2)
+
+// base properties throw 1 when set; derived, 2
+shouldBe("derived2.baseDup = 0", 2);
+shouldBe("derived2.baseOnly = 0", 1);
+shouldBe("derived2.derivedOnly = 0", 2)
+shouldBe("derived2.protoDup = 0", 2);
+
+shouldBe('Object.getOwnPropertyDescriptor(derived, "baseProto")', undefined);
+shouldBe('Object.getOwnPropertyDescriptor(derived, "baseProtoDup")', undefined);
+var baseDupDescriptor = Object.getOwnPropertyDescriptor(derived, "baseDup");
+shouldBe('typeof baseDupDescriptor', "object");
+shouldBe('baseDupDescriptor.value', derived.baseDup);
+shouldBe('baseDupDescriptor.configurable', true);
+shouldBe('baseDupDescriptor.enumerable', false);
+var baseOnlyDescriptor = Object.getOwnPropertyDescriptor(derived, "baseOnly");
+shouldBe('typeof baseOnlyDescriptor', "object");
+shouldBe('baseOnlyDescriptor.value', derived.baseOnly);
+shouldBe('baseOnlyDescriptor.configurable', true);
+shouldBe('baseOnlyDescriptor.enumerable', false);
+shouldBe('Object.getOwnPropertyDescriptor(derived, "protoOnly")', undefined);
+var protoDupDescriptor = Object.getOwnPropertyDescriptor(derived, "protoDup");
+shouldBe('typeof protoDupDescriptor', "object");
+shouldBe('protoDupDescriptor.value', derived.protoDup);
+shouldBe('protoDupDescriptor.configurable', true);
+shouldBe('protoDupDescriptor.enumerable', false);
+var derivedOnlyDescriptor = Object.getOwnPropertyDescriptor(derived, "derivedOnly");
+shouldBe('typeof derivedOnlyDescriptor', "object");
+shouldBe('derivedOnlyDescriptor.value', derived.derivedOnly);
+shouldBe('derivedOnlyDescriptor.configurable', true);
+shouldBe('derivedOnlyDescriptor.enumerable', false);
+
 shouldBe("undefined instanceof MyObject", false);
 EvilExceptionObject.hasInstance = function f() { return f(); };
 EvilExceptionObject.__proto__ = undefined;