Implement select listbox using shadow DOM

Source/core/html/shadow/ShadowElementNames.h

 /*
  * 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 33 matching lines @@
 const AtomicString& clearButton();
 const AtomicString& editingViewPort();
 const AtomicString& innerEditor();
 const AtomicString& pickerIndicator();
 const AtomicString& placeholder();
 const AtomicString& searchDecoration();
 const AtomicString& sliderThumb();
 const AtomicString& sliderTrack();
 const AtomicString& speechButton();
 const AtomicString& textFieldContainer();
+const AtomicString& optGroupLabel();
 
 }
 
 }
 
 #endif