Make sure getAttribute() / setAttribute() callers use AtomicStrings

Source/core/html/HTMLTrackElement.h

 /*
  * Copyright (C) 2011 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.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 20 matching lines @@
 #include "core/html/track/TextTrack.h"
 
 namespace WebCore {
 
 class HTMLMediaElement;
 
 class HTMLTrackElement FINAL : public HTMLElement, public TextTrackClient {
 public:
     static PassRefPtr<HTMLTrackElement> create(Document&);
 
-    String kind();
-    void setKind(const String&);
+    const AtomicString& kind();
+    void setKind(const AtomicString&);
 
     enum ReadyState { NONE = 0, LOADING = 1, LOADED = 2, TRACK_ERROR = 3 };
     ReadyState readyState();
     void setReadyState(ReadyState);
 
     TextTrack* track();
 
     void scheduleLoad();
 
     enum LoadStatus { Failure, Success };
@@ skipping 29 matching lines @@
 
     RefPtr<LoadableTextTrack> m_track;
     Timer<HTMLTrackElement> m_loadTimer;
 };
 
 DEFINE_NODE_TYPE_CASTS(HTMLTrackElement, hasTagName(HTMLNames::trackTag));
 
 }
 
 #endif