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

Source/bindings/v8/V8WindowShell.cpp

 /*
  * Copyright (C) 2008, 2009, 2011 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 60 matching lines @@
 {
     ASSERT(V8Document::toNative(wrapper) == document);
     ASSERT(!document->isHTMLDocument() || (V8Document::toNative(v8::Handle<v8::Object>::Cast(wrapper->GetPrototype())) == document));
 }
 
 static void setInjectedScriptContextDebugId(v8::Handle<v8::Context> targetContext, int debugId)
 {
     V8PerContextDebugData::setContextDebugData(targetContext, "injected", debugId);
 }
 
-PassOwnPtr<V8WindowShell> V8WindowShell::create(LocalFrame* frame, DOMWrapperWorld& world, v8::Isolate* isolate)
+PassOwnPtr<V8WindowShell> V8WindowShell::create(LocalFrame* frame, PassRefPtr<DOMWrapperWorld> world, v8::Isolate* isolate)
 {
-    return adoptPtr(new V8WindowShell(frame, &world, isolate));
+    return adoptPtr(new V8WindowShell(frame, world, isolate));
 }
 
 V8WindowShell::V8WindowShell(LocalFrame* frame, PassRefPtr<DOMWrapperWorld> world, v8::Isolate* isolate)
     : m_frame(frame)
     , m_world(world)
     , m_isolate(isolate)
 {
 }
 
 void V8WindowShell::disposeContext(GlobalDetachmentBehavior behavior)
@@ skipping 404 matching lines @@
 void V8WindowShell::updateSecurityOrigin(SecurityOrigin* origin)
 {
     ASSERT(m_world->isMainWorld());
     if (!m_perContextData)
         return;
     v8::HandleScope handleScope(m_isolate);
     setSecurityToken(origin);
 }
 
 } // WebCore