ement('iframe');
    t.add_cleanup(() => iframe.remove());
    iframe.src = `${REMOTE_ORIGIN}/resource-timing/resources/green.html`;
    document.body.appendChild(iframe);
    const entry = await observe_entry(iframe.src);
    invariants.assert_tao_failure_resource(entry);
  }, "A cross-origin iframe should report an opaque RT entry");

  promise_test(async t => {
    const iframe = document.createElement('iframe');
    t.add_cleanup(() => iframe.remove());
    iframe.src = `${REMOTE_ORIGIN}/resource-timing