tc->IsOnlyWhitespace(&result);
result = tc->IsOnlyWhitespace();
nsHTMLCopyEncoder::IsEmptyTextContent(nsIDOMNode* aNode){  PRBool result = PR_FALSE;  nsCOMPtr<nsITextContent> tc(do_QueryInterface(aNode));  if (tc) {    tc->IsOnlyWhitespace(&result);  }  return result;}