if (mFrameLoader || !mParent) {
if (mFrameLoader || !mParent || !mDocument) {
nsHTMLIFrameElement::EnsureFrameLoader(){  if (mFrameLoader || !mParent) {    return NS_OK;  }  nsresult rv = NS_NewFrameLoader(getter_AddRefs(mFrameLoader));  NS_ENSURE_SUCCESS(rv, rv);  mFrameLoader->Init(this);  return NS_OK;}