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

Source/core/loader/FrameLoaderClient.h

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  * 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.
@@ skipping 152 matching lines @@
         enum DetachedPluginPolicy {
             FailOnDetachedPlugin,
             AllowDetachedPlugin,
         };
         virtual PassRefPtr<Widget> createPlugin(HTMLPlugInElement*, const KURL&, const Vector<String>&, const Vector<String>&, const String&, bool loadManually, DetachedPluginPolicy) = 0;
 
         virtual PassRefPtr<Widget> createJavaAppletWidget(HTMLAppletElement*, const KURL& baseURL, const Vector<String>& paramNames, const Vector<String>& paramValues) = 0;
 
         virtual ObjectContentType objectContentType(const KURL&, const String& mimeType, bool shouldPreferPlugInsForImages) = 0;
 
-        virtual void dispatchDidClearWindowObjectInWorld(DOMWrapperWorld&) = 0;
+        virtual void dispatchDidClearWindowObjectInWorld(DOMWrapperWorld*) = 0;
         virtual void documentElementAvailable() = 0;
 
         virtual void didCreateScriptContext(v8::Handle<v8::Context>, int extensionGroup, int worldId) = 0;
         virtual void willReleaseScriptContext(v8::Handle<v8::Context>, int worldId) = 0;
         virtual bool allowScriptExtension(const String& extensionName, int extensionGroup, int worldId) = 0;
 
         virtual void didChangeScrollOffset() { }
         virtual void didUpdateCurrentHistoryItem() { }
 
         virtual bool allowScript(bool enabledPerSettings) { return enabledPerSettings; }
@@ skipping 42 matching lines @@
         virtual PassOwnPtr<blink::WebApplicationCacheHost> createApplicationCacheHost(blink::WebApplicationCacheHostClient*) = 0;
 
         virtual void didStopAllLoaders() { }
 
         virtual bool isFrameLoaderClientImpl() const { return false; }
     };
 
 } // namespace WebCore
 
 #endif // FrameLoaderClient_h