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diff --git a/JavaScriptCore/wtf/PageReservation.h b/JavaScriptCore/wtf/PageReservation.h
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+/*
+ * Copyright (C) 2010 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 PageReservation_h
+#define PageReservation_h
+
+#include <wtf/PageAllocation.h>
+
+namespace WTF {
+
+/*
+    PageReservation
+
+    Like PageAllocation, the PageReservation class provides a cross-platform memory
+    allocation interface, but with a set of capabilities more similar to that of
+    VirtualAlloc than posix mmap.  PageReservation can be used to allocate virtual
+    memory without committing physical memory pages using PageReservation::reserve.
+    Following a call to reserve all memory in the region is in a decommited state,
+    in which the memory should not be used (accessing the memory may cause a fault).
+
+    Before using memory it must be committed by calling commit, which is passed start
+    and size values (both of which require system page size granularity).  One the
+    committed memory is no longer needed 'decommit' may be called to return the
+    memory to its devommitted state.  Commit should only be called on memory that is
+    currently decommitted, and decommit should only be called on memory regions that
+    are currently committed.  All memory should be decommited before the reservation
+    is deallocated.  Values in memory may not be retained accross a pair of calls if
+    the region of memory is decommitted and then committed again.
+
+    Where HAVE(PAGE_ALLOCATE_AT) is available a PageReservation::reserveAt method
+    also exists, with behaviour mirroring PageAllocation::allocateAt.
+
+    Memory protection should not be changed on decommitted memory, and if protection
+    is changed on memory while it is committed it should be returned to the orignal
+    protection before decommit is called.
+
+    Note: Inherits from PageAllocation privately to prevent clients accidentally
+    calling PageAllocation::deallocate on a PageReservation.
+*/
+class PageReservation : private PageAllocation {
+public:
+    PageReservation()
+    {
+    }
+
+    using PageAllocation::operator!;
+    using PageAllocation::base;
+    using PageAllocation::size;
+
+    bool commit(void* start, size_t size)
+    {
+        ASSERT(m_base);
+        ASSERT(isPageAligned(start));
+        ASSERT(isPageAligned(size));
+
+        bool commited = systemCommit(start, size);
+#ifndef NDEBUG
+        if (commited)
+            m_committed += size;
+#endif
+        return commited;
+    }
+    void decommit(void* start, size_t size)
+    {
+        ASSERT(m_base);
+        ASSERT(isPageAligned(start));
+        ASSERT(isPageAligned(size));
+
+#ifndef NDEBUG
+        m_committed -= size;
+#endif
+        systemDecommit(start, size);
+    }
+
+    static PageReservation reserve(size_t size, Usage usage = UnknownUsage, bool writable = true, bool executable = false)
+    {
+        ASSERT(isPageAligned(size));
+        return systemReserve(size, usage, writable, executable);
+    }
+
+#if HAVE(PAGE_ALLOCATE_AT)
+    static PageReservation reserveAt(void* address, bool fixed, size_t size, Usage usage = UnknownUsage, bool writable = true, bool executable = false)
+    {
+        ASSERT(isPageAligned(address));
+        ASSERT(isPageAligned(size));
+        return systemReserveAt(address, fixed, size, usage, writable, executable);
+    }
+#endif
+
+    void deallocate()
+    {
+        ASSERT(m_base);
+        ASSERT(!m_committed);
+        systemDeallocate(false);
+    }
+
+#ifndef NDEBUG
+    using PageAllocation::lastError;
+#endif
+
+private:
+#if OS(SYMBIAN)
+    PageReservation(void* base, size_t size, RChunk* chunk)
+        : PageAllocation(base, size, chunk)
+#else
+    PageReservation(void* base, size_t size)
+        : PageAllocation(base, size)
+#endif
+#ifndef NDEBUG
+        , m_committed(0)
+#endif
+    {
+    }
+
+    bool systemCommit(void*, size_t);
+    void systemDecommit(void*, size_t);
+    static PageReservation systemReserve(size_t, Usage, bool, bool);
+#if HAVE(PAGE_ALLOCATE_AT)
+    static PageReservation systemReserveAt(void*, bool, size_t, Usage, bool, bool);
+#endif
+
+#if HAVE(VIRTUALALLOC)
+    DWORD m_protection;
+#endif
+#ifndef NDEBUG
+    size_t m_committed;
+#endif
+};
+
+
+#if HAVE(MMAP)
+
+
+inline bool PageReservation::systemCommit(void* start, size_t size)
+{
+#if HAVE(MADV_FREE_REUSE)
+    while (madvise(start, size, MADV_FREE_REUSE) == -1 && errno == EAGAIN) { }
+#else
+    UNUSED_PARAM(start);
+    UNUSED_PARAM(size);
+#endif
+    return true;
+}
+
+inline void PageReservation::systemDecommit(void* start, size_t size)
+{
+#if HAVE(MADV_FREE_REUSE)
+    while (madvise(start, size, MADV_FREE_REUSABLE) == -1 && errno == EAGAIN) { }
+#elif HAVE(MADV_FREE)
+    while (madvise(start, size, MADV_FREE) == -1 && errno == EAGAIN) { }
+#elif HAVE(MADV_DONTNEED)
+    while (madvise(start, size, MADV_DONTNEED) == -1 && errno == EAGAIN) { }
+#else
+    UNUSED_PARAM(start);
+    UNUSED_PARAM(size);
+#endif
+}
+
+inline PageReservation PageReservation::systemReserve(size_t size, Usage usage, bool writable, bool executable)
+{
+    return systemReserveAt(0, false, size, usage, writable, executable);
+}
+
+inline PageReservation PageReservation::systemReserveAt(void* address, bool fixed, size_t size, Usage usage, bool writable, bool executable)
+{
+    void* base = systemAllocateAt(address, fixed, size, usage, writable, executable).base();
+#if HAVE(MADV_FREE_REUSE)
+    // When using MADV_FREE_REUSE we keep all decommitted memory marked as REUSABLE.
+    // We call REUSE on commit, and REUSABLE on decommit.
+    if (base)
+        while (madvise(base, size, MADV_FREE_REUSABLE) == -1 && errno == EAGAIN) { }
+#endif
+    return PageReservation(base, size);
+}
+
+
+#elif HAVE(VIRTUALALLOC)
+
+
+inline bool PageReservation::systemCommit(void* start, size_t size)
+{
+    return VirtualAlloc(start, size, MEM_COMMIT, m_protection) == start;
+}
+
+inline void PageReservation::systemDecommit(void* start, size_t size)
+{
+    VirtualFree(start, size, MEM_DECOMMIT);
+}
+
+inline PageReservation PageReservation::systemReserve(size_t size, Usage usage, bool writable, bool executable)
+{
+    // Record the protection for use during commit.
+    DWORD protection = executable ?
+        (writable ? PAGE_EXECUTE_READWRITE : PAGE_EXECUTE_READ) :
+        (writable ? PAGE_READWRITE : PAGE_READONLY);
+    PageReservation reservation(VirtualAlloc(0, size, MEM_RESERVE, protection), size);
+    reservation.m_protection = protection;
+    return reservation;
+}
+
+
+#elif OS(SYMBIAN)
+
+
+inline bool PageReservation::systemCommit(void* start, size_t size)
+{
+    intptr_t offset = reinterpret_cast<intptr_t>(start) - reinterpret_cast<intptr_t>(m_base);
+    m_chunk->Commit(offset, size);
+    return true;
+}
+
+inline void PageReservation::systemDecommit(void* start, size_t size)
+{
+    intptr_t offset = reinterpret_cast<intptr_t>(start) - reinterpret_cast<intptr_t>(m_base);
+    m_chunk->Decommit(offset, size);
+}
+
+inline PageReservation PageReservation::systemReserve(size_t size, Usage usage, bool writable, bool executable)
+{
+    RChunk* rchunk = new RChunk();
+    if (executable)
+        rchunk->CreateLocalCode(0, size);
+    else
+        rchunk->CreateDisconnectedLocal(0, 0, size);
+    return PageReservation(rchunk->Base(), size, rchunk);
+}
+
+
+#endif
+
+
+}
+
+using WTF::PageReservation;
+
+#endif // PageReservation_h