Apply FINAL to the RenderObject hierarchy.

Source/core/rendering/RenderMediaControlElements.h

 /*
  * Copyright (C) 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2012 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 18 matching lines @@
 #define RenderMediaControlElements_h
 
 #if ENABLE(VIDEO)
 
 #include "MediaControlElements.h"
 #include "RenderBlock.h"
 #include "RenderFlexibleBox.h"
 
 namespace WebCore {
 
-class RenderTextTrackContainerElement : public RenderBlock {
+class RenderTextTrackContainerElement FINAL : public RenderBlock {
 public:
     RenderTextTrackContainerElement(Element*);
 
 private:
     virtual void layout();
 };
 
 
 } // namespace WebCore
 
 #endif // ENABLE(VIDEO)
 
 #endif // RenderMediaControlElements_h