if (mDocument) {
if (documentChanging && mDocument) {
nsHTMLLabelElement::SetDocument(nsIDocument* aDocument, PRBool aDeep,                                PRBool aCompileEventHandlers){  // Unregister the access key for the old document.  if (mDocument) {    RegUnRegAccessKey(PR_FALSE);  }  nsresult rv = nsGenericHTMLContainerFormElement::SetDocument(aDocument,                                                 aDeep, aCompileEventHandlers);  // Register the access key for the new document.  if (mDocument) {    RegUnRegAccessKey(PR_TRUE);  }  return rv;}