Remove some dead code in dom/

Source/core/dom/DOMException.cpp

 /*
  * 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
@@ skipping 118 matching lines @@
 String DOMException::getErrorMessage(ExceptionCode ec)
 {
     const CoreException* entry = getErrorEntry(ec);
     ASSERT(entry);
     if (!entry)
         return "Unknown error.";
 
     return entry->message;
 }
 
-unsigned short DOMException::getLegacyErrorCode(ExceptionCode ec)
-{
-    const CoreException* entry = getErrorEntry(ec);
-    ASSERT(entry);
-
-    return (entry && entry->code) ? entry->code : 0;
-}
-
 } // namespace WebCore