nsresult rv = NS_NewXMLElement(getter_AddRefs(xmlContent), tag);
nsresult rv = NS_NewXMLElement(getter_AddRefs(xmlContent), aNodeInfo);
XMLElementFactoryImpl::CreateInstanceByTag(const nsString& aTag, nsIContent** aResult){  nsCOMPtr<nsIAtom> tag = dont_AddRef(NS_NewAtom(aTag));  if (! tag)    return NS_ERROR_OUT_OF_MEMORY;  nsCOMPtr<nsIXMLContent> xmlContent;  nsresult rv = NS_NewXMLElement(getter_AddRefs(xmlContent), tag);  nsCOMPtr<nsIContent> result = do_QueryInterface(xmlContent);  *aResult = result;  NS_IF_ADDREF(*aResult);  return rv; }