Remove some dead code from html/

Source/core/html/MediaController.h

 /*
  * Copyright (C) 2011 Apple 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:
  * 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 32 matching lines @@
 class ExecutionContext;
 
 class MediaController FINAL : public RefCounted<MediaController>, public ScriptWrappable, public EventTargetWithInlineData {
     REFCOUNTED_EVENT_TARGET(MediaController);
 public:
     static PassRefPtr<MediaController> create(ExecutionContext*);
     virtual ~MediaController();
 
     void addMediaElement(HTMLMediaElement*);
     void removeMediaElement(HTMLMediaElement*);
-    bool containsMediaElement(HTMLMediaElement*) const;
 
     PassRefPtr<TimeRanges> buffered() const;
     PassRefPtr<TimeRanges> seekable() const;
     PassRefPtr<TimeRanges> played();
 
     double duration() const;
     double currentTime() const;
     void setCurrentTime(double, ExceptionState&);
 
     bool paused() const { return m_paused; }
@@ skipping 58 matching lines @@
     mutable Timer<MediaController> m_clearPositionTimer;
     OwnPtr<Clock> m_clock;
     ExecutionContext* m_executionContext;
     Timer<MediaController> m_timeupdateTimer;
     double m_previousTimeupdateTime;
 };
 
 } // namespace WebCore
 
 #endif