Rename the Custom Elements runtime feature to "CustomElements".

Source/web/WebRuntimeFeatures.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 366 matching lines @@
     RuntimeEnabledFeatures::setHTMLImportsEnabled(enable);
 }
 
 bool WebRuntimeFeatures::isHTMLImportsEnabled()
 {
     return RuntimeEnabledFeatures::htmlImportsEnabled();
 }
 
 void WebRuntimeFeatures::enableCustomElements(bool enable)
 {
-    RuntimeEnabledFeatures::setCustomDOMElementsEnabled(enable);
+    RuntimeEnabledFeatures::setCustomElementsEnabled(enable);
 }
 
 void WebRuntimeFeatures::enableOverlayScrollbars(bool enable)
 {
     RuntimeEnabledFeatures::setOverlayScrollbarsEnabled(enable);
 }
 
 } // namespace WebKit