.body.appendChild(iframe);
  const result = await iframe_reply;

  assert_equals(result.data, "document-domain-is-disallowed");
}, "srcdoc");

promise_test_parallel(async test => {
  const iframe = document.createElement("iframe");
  iframe.csp = sandbox_policy;

  const blob = new Blob([check_sandbox_script], { type: "text/html" });

  iframe.src = URL.createObjectURL(blob);

  const iframe_reply = future(window, "message", iframe);
  document.body.appendChild(iframe);
  const result = await iframe_reply;
