Change RefPtr<DOMWrapperWorld> that causes reference cycles to DOMWrapperWorld*

Source/bindings/v8/DOMRequestState.h

 /*
  * Copyright (C) 2012 Google 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
@@ skipping 29 matching lines @@
         : m_isolate(toIsolate(executionContext))
         , m_executionContext(executionContext)
         , m_world(DOMWrapperWorld::current(m_isolate))
     {
         ASSERT(m_executionContext);
     }
 
     void clear()
     {
         m_executionContext = 0;
-        m_world.clear();
+        m_world = 0;
     }
 
     class Scope {
     public:
         explicit Scope(DOMRequestState& state)
             : m_handleScope(state.isolate())
             , m_contextScope(state.context())
         {
         }
     private:
         v8::HandleScope m_handleScope;
         v8::Context::Scope m_contextScope;
     };
 
     v8::Local<v8::Context> context()
     {
         ASSERT(m_executionContext);
-        return toV8Context(m_executionContext, m_world.get());
+        return toV8Context(m_executionContext, m_world);
     }
 
     v8::Isolate* isolate() const
     {
         return m_isolate;
     }
 
     bool isValid() const { return m_executionContext; }
 
 private:
     v8::Isolate* m_isolate;
     ExecutionContext* m_executionContext;
-    RefPtr<DOMWrapperWorld> m_world;
+    DOMWrapperWorld* m_world;
 };
 
 }
 #endif