if (!mElement) { return NS_OK; }
nsXFormsLabelElement::OnStartRequest(nsIRequest *aRequest,                                     nsISupports *aContext){  // Only handle data from text files for now.  Cancel any other requests.  nsCOMPtr<nsIChannel> channel(do_QueryInterface(aRequest));  if (channel) {    nsCAutoString type;    channel->GetContentType(type);    if (!type.EqualsLiteral("text/plain"))      return NS_ERROR_ILLEGAL_VALUE;  }  mSrcAttrText.Truncate();  return NS_OK;}