bindings: Introduces type-check for the internal pointers.

Source/bindings/core/v8/custom/V8MutationObserverCustom.cpp

 /*
  * Copyright (C) 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 49 matching lines @@
 
     v8::Handle<v8::Object> wrapper = info.Holder();
 
     OwnPtr<MutationCallback> callback = V8MutationCallback::create(v8::Handle<v8::Function>::Cast(arg), wrapper, ScriptState::current(info.GetIsolate()));
     RefPtrWillBeRawPtr<MutationObserver> observer = MutationObserver::create(callback.release());
 
     V8DOMWrapper::associateObjectWithWrapper<V8MutationObserver>(observer.release(), &wrapperTypeInfo, wrapper, info.GetIsolate(), WrapperConfiguration::Dependent);
     info.GetReturnValue().Set(wrapper);
 }
 
-void V8MutationObserver::visitDOMWrapper(void* object, const v8::Persistent<v8::Object>& wrapper, v8::Isolate* isolate)
+void V8MutationObserver::visitDOMWrapper(ScriptWrappableBase* internalPointer, const v8::Persistent<v8::Object>& wrapper, v8::Isolate* isolate)
 {
-    MutationObserver* observer = static_cast<MutationObserver*>(object);
+    MutationObserver* observer = fromInternalPointer(internalPointer);
     WillBeHeapHashSet<RawPtrWillBeMember<Node> > observedNodes = observer->getObservedNodes();
     for (WillBeHeapHashSet<RawPtrWillBeMember<Node> >::iterator it = observedNodes.begin(); it != observedNodes.end(); ++it) {
         v8::UniqueId id(reinterpret_cast<intptr_t>(V8GCController::opaqueRootForGC(*it, isolate)));
         isolate->SetReferenceFromGroup(id, wrapper);
     }
 }
 
 } // namespace blink