frame.src =
    `data:text/html,${encodeURI(check_sandbox_script)}`;

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

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

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

  const iframe_reply = future(window, "message", iframe);
  document