Fix virtual/override/final usage in Source/core/html/.

Source/core/html/track/TextTrackContainer.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 34 matching lines @@
     // layout when the media controls become visible, to avoid overlapping them.
     enum ExposingControls {
         DidNotStartExposingControls,
         DidStartExposingControls
     };
     void updateDisplay(HTMLMediaElement&, ExposingControls);
 
 private:
     TextTrackContainer(Document&);
 
-    virtual bool isTextTrackContainer() const override { return true; }
+    bool isTextTrackContainer() const override { return true; }
 
-    virtual LayoutObject* createLayoutObject(const ComputedStyle&) override;
+    LayoutObject* createLayoutObject(const ComputedStyle&) override;
 };
 
 DEFINE_ELEMENT_TYPE_CASTS(TextTrackContainer, isTextTrackContainer());
 
 } // namespace blink
 
 #endif // TextTrackContainer_h