Inherit EventTarget interface instead of duplicating its code

Source/modules/mediastream/MediaStreamTrack.h

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  * Copyright (C) 2011 Ericsson AB. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 25 matching lines @@
 #include "wtf/RefCounted.h"
 #include "wtf/RefPtr.h"
 #include "wtf/Vector.h"
 #include "wtf/text/WTFString.h"
 
 namespace WebCore {
 
 class MediaStreamComponent;
 class MediaStreamTrackSourcesCallback;
 
-class MediaStreamTrack : public RefCounted<MediaStreamTrack>, public ScriptWrappable, public ActiveDOMObject, public EventTarget, public MediaStreamSource::Observer {
+class MediaStreamTrack : public EventTarget, public RefCounted<MediaStreamTrack>, public ScriptWrappable, public ActiveDOMObject, public MediaStreamSource::Observer {
 public:
     static PassRefPtr<MediaStreamTrack> create(ScriptExecutionContext*, MediaStreamComponent*);
     virtual ~MediaStreamTrack();
 
     String kind() const;
     String id() const;
     String label() const;
 
     bool enabled() const;
     void setEnabled(bool);
@@ skipping 36 matching lines @@
 
     bool m_stopped;
     RefPtr<MediaStreamComponent> m_component;
 };
 
 typedef Vector<RefPtr<MediaStreamTrack> > MediaStreamTrackVector;
 
 } // namespace WebCore
 
 #endif // MediaStreamTrack_h