NS_IMETHOD AttributeChanged(nsIDocument *aDocument, nsIContent *aContent, PRInt32 aNameSpaceID, nsIAtom *aAttribute, PRInt32 aModType, nsChangeHint aHint) { return NS_OK; }
NS_IMPL_NSIDOCUMENTOBSERVER_CONTENT(HTMLContentSink)
  NS_IMETHOD AttributeChanged(nsIDocument *aDocument, nsIContent *aContent,                              PRInt32 aNameSpaceID, nsIAtom *aAttribute,                              PRInt32 aModType, nsChangeHint aHint)  {    return NS_OK;  }