Fix RefPtr's move assignment operator

Source/wtf/RefPtr.h

 /*
  *  Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2013 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
@@ skipping 93 matching lines @@
     template<typename T> inline RefPtr<T>& RefPtr<T>::operator=(const RefPtr& o)
     {
         RefPtr ptr = o;
         swap(ptr);
         return *this;
     }
 
 #if COMPILER_SUPPORTS(CXX_RVALUE_REFERENCES)
     template<typename T> inline RefPtr<T>& RefPtr<T>::operator=(RefPtr&& o)
     {
-        swap(o);
+        // FIXME: Instead of explicitly casting to RefPtr&& here, we should use std::move, but that requires us to
+        // have a standard library that supports move semantics.
+        RefPtr ptr = static_cast<RefPtr&&>(o);
+        swap(ptr);
         return *this;
     }
 #endif
 
     template<typename T> template<typename U> inline RefPtr<T>& RefPtr<T>::operator=(const RefPtr<U>& o)
     {
         RefPtr ptr = o;
         swap(ptr);
         return *this;
     }
@@ skipping 87 matching lines @@
     private:
         T* m_ptr;
     };
 
 } // namespace WTF
 
 using WTF::RefPtr;
 using WTF::static_pointer_cast;
 
 #endif // WTF_RefPtr_h