Make calls to AtomicString(const String&) explicit in html/

Source/core/html/track/TextTrackCueList.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 29 matching lines @@
     {
         return adoptRef(new TextTrackCueList);
     }
 
     ~TextTrackCueList() { }
 
     unsigned long length() const;
     unsigned long getCueIndex(TextTrackCue*) const;
 
     TextTrackCue* item(unsigned index) const;
-    TextTrackCue* getCueById(const String&) const;
+    TextTrackCue* getCueById(const AtomicString&) const;
     TextTrackCueList* activeCues();
 
     bool add(PassRefPtr<TextTrackCue>);
     bool remove(TextTrackCue*);
     bool contains(TextTrackCue*) const;
 
     bool updateCueIndex(TextTrackCue*);
 
 private:
     TextTrackCueList();
     bool add(PassRefPtr<TextTrackCue>, size_t, size_t);
     void clear();
     void invalidateCueIndexes(size_t);
 
     Vector<RefPtr<TextTrackCue> > m_list;
     RefPtr<TextTrackCueList> m_activeCues;
 
 };
 
 } // namespace WebCore
 
 #endif