Inherit EventTarget interface instead of duplicating its code

Source/bindings/v8/V8CustomElementLifecycleCallbacks.cpp

 /*
  * Copyright (C) 2013 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 102 matching lines @@
     element->setIsUpgradedCustomElement();
 
     v8::HandleScope handleScope;
     v8::Handle<v8::Context> context = toV8Context(scriptExecutionContext(), m_world.get());
     if (context.IsEmpty())
         return;
 
     v8::Context::Scope scope(context);
     v8::Isolate* isolate = context->GetIsolate();
 
-    v8::Handle<v8::Object> receiver = DOMDataStore::current(isolate)->get(element);
+    v8::Handle<v8::Object> receiver = DOMDataStore::current(isolate)->get<V8Element>(element);
     if (!receiver.IsEmpty()) {
         // Swizzle the prototype of the existing wrapper. We don't need to
         // worry about non-existent wrappers; they will get the right
         // prototype when wrapped.
         v8::Handle<v8::Object> prototype = m_prototype.newLocal(isolate);
         if (prototype.IsEmpty())
             return;
         receiver->SetPrototype(prototype);
     }
 
@@ skipping 71 matching lines @@
 
     v8::Handle<v8::Object> receiver = toV8(element, context->Global(), isolate).As<v8::Object>();
     ASSERT(!receiver.IsEmpty());
 
     v8::TryCatch exceptionCatcher;
     exceptionCatcher.SetVerbose(true);
     ScriptController::callFunctionWithInstrumentation(scriptExecutionContext(), callback, receiver, 0, 0);
 }
 
 } // namespace WebCore