Implement select listbox using shadow DOM

Source/core/html/shadow/ShadowElementNames.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 101 matching lines @@
     DEFINE_STATIC_LOCAL(AtomicString, name, ("speech", AtomicString::ConstructFromLiteral));
     return name;
 }
 
 const AtomicString& textFieldContainer()
 {
     DEFINE_STATIC_LOCAL(AtomicString, name, ("text-field-container", AtomicString::ConstructFromLiteral));
     return name;
 }
 
+const AtomicString& optGroupLabel()
+{
+    DEFINE_STATIC_LOCAL(AtomicString, name, ("optgroup-label", AtomicString::ConstructFromLiteral));
+    return name;
+}
+
 }
 
 }