Inherit EventTarget interface instead of duplicating its code

Source/modules/mediasource/MediaSourceBase.h

 /*
  * 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 24 matching lines @@
 #include "core/dom/EventTarget.h"
 #include "core/html/URLRegistry.h"
 #include "core/platform/graphics/MediaSourcePrivate.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/RefCounted.h"
 
 namespace WebCore {
 
 class GenericEventQueue;
 
-class MediaSourceBase : public RefCounted<MediaSourceBase>, public ActiveDOMObject, public EventTarget, public URLRegistrable {
+class MediaSourceBase : public EventTarget, public RefCounted<MediaSourceBase>, public ActiveDOMObject, public URLRegistrable {
 public:
     static const AtomicString& openKeyword();
     static const AtomicString& closedKeyword();
     static const AtomicString& endedKeyword();
 
     virtual ~MediaSourceBase();
 
     void setPrivateAndOpen(PassOwnPtr<MediaSourcePrivate>);
     void addedToRegistry();
     void removedFromRegistry();
@@ skipping 38 matching lines @@
 private:
     OwnPtr<MediaSourcePrivate> m_private;
     EventTargetData m_eventTargetData;
     AtomicString m_readyState;
     OwnPtr<GenericEventQueue> m_asyncEventQueue;
 };
 
 }
 
 #endif