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

Source/bindings/v8/V8Binding.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009 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 531 matching lines @@
 {
     DOMWindow* window = toDOMWindow(context);
     if (window && window->isCurrentlyDisplayedInFrame())
         return window->frame();
     // We return 0 here because |context| is detached from the LocalFrame. If we
     // did return |frame| we could get in trouble because the frame could be
     // navigated to another security origin.
     return 0;
 }
 
-v8::Local<v8::Context> toV8Context(ExecutionContext* context, DOMWrapperWorld& world)
+v8::Local<v8::Context> toV8Context(ExecutionContext* context, DOMWrapperWorld* world)
 {
     ASSERT(context);
     if (context->isDocument()) {
         if (LocalFrame* frame = toDocument(context)->frame())
             return frame->script().windowShell(world)->context();
     } else if (context->isWorkerGlobalScope()) {
         if (WorkerScriptController* script = toWorkerGlobalScope(context)->script())
             return script->context();
     }
     return v8::Local<v8::Context>();
 }
 
-v8::Local<v8::Context> toV8Context(v8::Isolate* isolate, LocalFrame* frame, DOMWrapperWorld& world)
+v8::Local<v8::Context> toV8Context(v8::Isolate* isolate, LocalFrame* frame, DOMWrapperWorld* world)
 {
     if (!frame)
         return v8::Local<v8::Context>();
     v8::Local<v8::Context> context = frame->script().windowShell(world)->context();
     if (context.IsEmpty())
         return v8::Local<v8::Context>();
     LocalFrame* attachedFrame= toFrameIfNotDetached(context);
     return frame == attachedFrame ? context : v8::Local<v8::Context>();
 }
 
@@ skipping 81 matching lines @@
 V8ExecutionScope::V8ExecutionScope(v8::Isolate* isolate)
     : m_handleScope(isolate)
     , m_context(v8::Context::New(isolate))
     , m_contextScope(m_context)
     , m_world(DOMWrapperWorld::create())
     , m_perContextData(V8PerContextData::create(m_context, m_world))
 {
 }
 
 } // namespace WebCore