Remove the mode getter/setter for in-band text tracks

Source/core/html/track/TextTrack.cpp

 /*
  * Copyright (C) 2011 Google Inc.  All rights reserved.
  * Copyright (C) 2011, 2012, 2013 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 84 matching lines @@
 }
 
 TextTrack::TextTrack(Document& document, TextTrackClient* client, const AtomicString& kind, const AtomicString& label, const AtomicString& language, TextTrackType type)
     : TrackBase(TrackBase::TextTrack)
     , m_cues(0)
     , m_regions(0)
     , m_document(&document)
     , m_mediaElement(0)
     , m_label(label)
     , m_language(language)
-    , m_mode(disabledKeyword().string())
+    , m_mode(disabledKeyword())
     , m_client(client)
     , m_trackType(type)
     , m_readinessState(NotLoaded)
     , m_trackIndex(invalidTrackIndex)
     , m_renderedTrackIndex(invalidTrackIndex)
     , m_hasBeenConfigured(false)
 {
     ScriptWrappable::init(this);
     setKind(kind);
 }
@@ skipping 364 matching lines @@
     return EventTargetNames::TextTrack;
 }
 
 ExecutionContext* TextTrack::executionContext() const
 {
     return m_document;
 }
 
 } // namespace WebCore