Revert of Make DOMWrapperWorld::current() return a reference instead of a pointer

Source/bindings/v8/V8Binding.h

 /*
 * Copyright (C) 2009 Google Inc. All rights reserved.
 * Copyright (C) 2012 Ericsson AB. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
@@ skipping 639 matching lines @@
 DOMWindow* toDOMWindow(v8::Handle<v8::Context>);
 DOMWindow* enteredDOMWindow(v8::Isolate*);
 DOMWindow* currentDOMWindow(v8::Isolate*);
 DOMWindow* callingDOMWindow(v8::Isolate*);
 ExecutionContext* toExecutionContext(v8::Handle<v8::Context>);
 ExecutionContext* currentExecutionContext(v8::Isolate*);
 ExecutionContext* callingExecutionContext(v8::Isolate*);
 
 // Returns a V8 context associated with a ExecutionContext and a DOMWrapperWorld.
 // This method returns an empty context if there is no frame or the frame is already detached.
-v8::Local<v8::Context> toV8Context(ExecutionContext*, DOMWrapperWorld&);
+v8::Local<v8::Context> toV8Context(ExecutionContext*, DOMWrapperWorld*);
 // Returns a V8 context associated with a LocalFrame and a DOMWrapperWorld.
 // This method returns an empty context if the frame is already detached.
-v8::Local<v8::Context> toV8Context(v8::Isolate*, LocalFrame*, DOMWrapperWorld&);
+v8::Local<v8::Context> toV8Context(v8::Isolate*, LocalFrame*, DOMWrapperWorld*);
 
 // Returns the frame object of the window object associated with
 // a context, if the window is currently being displayed in the LocalFrame.
 LocalFrame* toFrameIfNotDetached(v8::Handle<v8::Context>);
 
 // If the current context causes out of memory, JavaScript setting
 // is disabled and it returns true.
 bool handleOutOfMemory();
 v8::Local<v8::Value> handleMaxRecursionDepthExceeded(v8::Isolate*);
 void crashIfV8IsDead();
@@ skipping 83 matching lines @@
     v8::HandleScope m_handleScope;
     v8::Handle<v8::Context> m_context;
     v8::Context::Scope m_contextScope;
     RefPtr<DOMWrapperWorld> m_world;
     OwnPtr<V8PerContextData> m_perContextData;
 };
 
 } // namespace WebCore
 
 #endif // V8Binding_h