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

Source/bindings/v8/DOMDataStore.cpp

 /*
  * Copyright (C) 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 33 matching lines @@
 }
 
 DOMDataStore::~DOMDataStore()
 {
     ASSERT(!m_isMainWorld); // We never actually destruct the main world's DOMDataStore.
     m_wrapperMap.clear();
 }
 
 DOMDataStore& DOMDataStore::current(v8::Isolate* isolate)
 {
-    return DOMWrapperWorld::world(isolate->GetCurrentContext())->domDataStore();
+    return DOMWrapperWorld::current(isolate).domDataStore();
 }
 
 } // namespace WebCore