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diff --git a/Source/JavaScriptCore/wtf/PassRefPtr.h b/Source/JavaScriptCore/wtf/PassRefPtr.h
new file mode 100644
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+++ b/Source/JavaScriptCore/wtf/PassRefPtr.h
@@ -0,0 +1,245 @@
+/*
+ *  Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Library General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2 of the License, or (at your option) any later version.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Library General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Library General Public License
+ *  along with this library; see the file COPYING.LIB.  If not, write to
+ *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ *  Boston, MA 02110-1301, USA.
+ *
+ */
+
+#ifndef WTF_PassRefPtr_h
+#define WTF_PassRefPtr_h
+
+#include "AlwaysInline.h"
+#include "NullPtr.h"
+
+namespace WTF {
+
+    template<typename T> class RefPtr;
+    template<typename T> class PassRefPtr;
+    template<typename T> PassRefPtr<T> adoptRef(T*);
+
+    inline void adopted(const void*) { }
+
+#if !PLATFORM(QT)
+    #define REF_DEREF_INLINE ALWAYS_INLINE
+#else
+    // Using ALWAYS_INLINE broke the Qt build. This may be a GCC bug.
+    // See https://bugs.webkit.org/show_bug.cgi?id=37253 for details.
+    #define REF_DEREF_INLINE inline
+#endif
+
+    template<typename T> REF_DEREF_INLINE void refIfNotNull(T* ptr)
+    {
+        if (LIKELY(ptr != 0))
+            ptr->ref();
+    }
+
+    template<typename T> REF_DEREF_INLINE void derefIfNotNull(T* ptr)
+    {
+        if (LIKELY(ptr != 0))
+            ptr->deref();
+    }
+
+    #undef REF_DEREF_INLINE
+
+    template<typename T> class PassRefPtr {
+    public:
+        PassRefPtr() : m_ptr(0) { }
+        PassRefPtr(T* ptr) : m_ptr(ptr) { refIfNotNull(ptr); }
+        // It somewhat breaks the type system to allow transfer of ownership out of
+        // a const PassRefPtr. However, it makes it much easier to work with PassRefPtr
+        // temporaries, and we don't have a need to use real const PassRefPtrs anyway.
+        PassRefPtr(const PassRefPtr& o) : m_ptr(o.leakRef()) { }
+        template<typename U> PassRefPtr(const PassRefPtr<U>& o) : m_ptr(o.leakRef()) { }
+
+        ALWAYS_INLINE ~PassRefPtr() { derefIfNotNull(m_ptr); }
+
+        template<typename U> PassRefPtr(const RefPtr<U>&);
+        
+        T* get() const { return m_ptr; }
+
+        T* leakRef() const WARN_UNUSED_RETURN;
+
+        T& operator*() const { return *m_ptr; }
+        T* operator->() const { return m_ptr; }
+
+        bool operator!() const { return !m_ptr; }
+
+        // This conversion operator allows implicit conversion to bool but not to other integer types.
+        typedef T* (PassRefPtr::*UnspecifiedBoolType);
+        operator UnspecifiedBoolType() const { return m_ptr ? &PassRefPtr::m_ptr : 0; }
+
+        PassRefPtr& operator=(const PassRefPtr&) { COMPILE_ASSERT(!sizeof(T*), PassRefPtr_should_never_be_assigned_to); return *this; }
+
+        friend PassRefPtr adoptRef<T>(T*);
+
+    private:
+        // adopting constructor
+        PassRefPtr(T* ptr, bool) : m_ptr(ptr) { }
+
+        mutable T* m_ptr;
+    };
+    
+    // NonNullPassRefPtr: Optimized for passing non-null pointers. A NonNullPassRefPtr
+    // begins life non-null, and can only become null through a call to leakRef()
+    // or clear().
+
+    // FIXME: NonNullPassRefPtr could just inherit from PassRefPtr. However,
+    // if we use inheritance, GCC's optimizer fails to realize that destruction
+    // of a released NonNullPassRefPtr is a no-op. So, for now, just copy the
+    // most important code from PassRefPtr.
+    template<typename T> class NonNullPassRefPtr {
+    public:
+        NonNullPassRefPtr(T* ptr)
+            : m_ptr(ptr)
+        {
+            ASSERT(m_ptr);
+            m_ptr->ref();
+        }
+
+        template<typename U> NonNullPassRefPtr(const RefPtr<U>& o)
+            : m_ptr(o.get())
+        {
+            ASSERT(m_ptr);
+            m_ptr->ref();
+        }
+
+        NonNullPassRefPtr(const NonNullPassRefPtr& o)
+            : m_ptr(o.leakRef())
+        {
+            ASSERT(m_ptr);
+        }
+
+        template<typename U> NonNullPassRefPtr(const NonNullPassRefPtr<U>& o)
+            : m_ptr(o.leakRef())
+        {
+            ASSERT(m_ptr);
+        }
+
+        template<typename U> NonNullPassRefPtr(const PassRefPtr<U>& o)
+            : m_ptr(o.leakRef())
+        {
+            ASSERT(m_ptr);
+        }
+
+        ALWAYS_INLINE ~NonNullPassRefPtr() { derefIfNotNull(m_ptr); }
+
+        T* get() const { return m_ptr; }
+
+        T* leakRef() const WARN_UNUSED_RETURN { T* tmp = m_ptr; m_ptr = 0; return tmp; }
+
+        T& operator*() const { return *m_ptr; }
+        T* operator->() const { return m_ptr; }
+
+        NonNullPassRefPtr& operator=(const NonNullPassRefPtr&) { COMPILE_ASSERT(!sizeof(T*), NonNullPassRefPtr_should_never_be_assigned_to); return *this; }
+
+    private:
+        mutable T* m_ptr;
+    };
+
+    template<typename T> template<typename U> inline PassRefPtr<T>::PassRefPtr(const RefPtr<U>& o)
+        : m_ptr(o.get())
+    {
+        T* ptr = m_ptr;
+        refIfNotNull(ptr);
+    }
+
+    template<typename T> inline T* PassRefPtr<T>::leakRef() const
+    {
+        T* ptr = m_ptr;
+        m_ptr = 0;
+        return ptr;
+    }
+
+    template<typename T, typename U> inline bool operator==(const PassRefPtr<T>& a, const PassRefPtr<U>& b) 
+    { 
+        return a.get() == b.get(); 
+    }
+
+    template<typename T, typename U> inline bool operator==(const PassRefPtr<T>& a, const RefPtr<U>& b) 
+    { 
+        return a.get() == b.get(); 
+    }
+
+    template<typename T, typename U> inline bool operator==(const RefPtr<T>& a, const PassRefPtr<U>& b) 
+    { 
+        return a.get() == b.get(); 
+    }
+
+    template<typename T, typename U> inline bool operator==(const PassRefPtr<T>& a, U* b) 
+    { 
+        return a.get() == b; 
+    }
+    
+    template<typename T, typename U> inline bool operator==(T* a, const PassRefPtr<U>& b) 
+    {
+        return a == b.get(); 
+    }
+    
+    template<typename T, typename U> inline bool operator!=(const PassRefPtr<T>& a, const PassRefPtr<U>& b) 
+    { 
+        return a.get() != b.get(); 
+    }
+
+    template<typename T, typename U> inline bool operator!=(const PassRefPtr<T>& a, const RefPtr<U>& b) 
+    { 
+        return a.get() != b.get(); 
+    }
+
+    template<typename T, typename U> inline bool operator!=(const RefPtr<T>& a, const PassRefPtr<U>& b) 
+    { 
+        return a.get() != b.get(); 
+    }
+
+    template<typename T, typename U> inline bool operator!=(const PassRefPtr<T>& a, U* b)
+    {
+        return a.get() != b; 
+    }
+
+    template<typename T, typename U> inline bool operator!=(T* a, const PassRefPtr<U>& b) 
+    { 
+        return a != b.get(); 
+    }
+    
+    template<typename T> inline PassRefPtr<T> adoptRef(T* p)
+    {
+        adopted(p);
+        return PassRefPtr<T>(p, true);
+    }
+
+    template<typename T, typename U> inline PassRefPtr<T> static_pointer_cast(const PassRefPtr<U>& p) 
+    { 
+        return adoptRef(static_cast<T*>(p.leakRef())); 
+    }
+
+    template<typename T, typename U> inline PassRefPtr<T> const_pointer_cast(const PassRefPtr<U>& p) 
+    { 
+        return adoptRef(const_cast<T*>(p.leakRef())); 
+    }
+
+    template<typename T> inline T* getPtr(const PassRefPtr<T>& p)
+    {
+        return p.get();
+    }
+
+} // namespace WTF
+
+using WTF::PassRefPtr;
+using WTF::NonNullPassRefPtr;
+using WTF::adoptRef;
+using WTF::static_pointer_cast;
+using WTF::const_pointer_cast;
+
+#endif // WTF_PassRefPtr_h