Remove unused TextTrack virtual functions

Source/web/InbandTextTrackPrivateImpl.cpp

 /*
  * 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 46 matching lines @@
 WebCore::InbandTextTrackPrivate::Mode InbandTextTrackPrivateImpl::mode() const
 {
     return static_cast<WebCore::InbandTextTrackPrivate::Mode>(m_track->mode());
 }
 
 WebCore::InbandTextTrackPrivate::Kind InbandTextTrackPrivateImpl::kind() const
 {
     return static_cast<WebCore::InbandTextTrackPrivate::Kind>(m_track->kind());
 }
 
-bool InbandTextTrackPrivateImpl::isClosedCaptions() const
-{
-    return m_track->isClosedCaptions();
-}
-
 AtomicString InbandTextTrackPrivateImpl::label() const
 {
     return m_track->label();
 }
 
 AtomicString InbandTextTrackPrivateImpl::language() const
 {
     return m_track->language();
 }
 
@@ skipping 11 matching lines @@
     double start,
     double end,
     const WebString& id,
     const WebString& content,
     const WebString& settings)
 {
     client()->addWebVTTCue(this, start, end, id, content, settings);
 }
 
 } // namespace WebKit