sage({workerMessageOrigin: e.data, messageOrigin: e.origin}, \"*\"); };" +
      "new Worker(URL.createObjectURL(new Blob([\"" +
      "let bc2 = new BroadcastChannel('test'); bc2.postMessage('ping'); " +
      "bc2.onmessage = e => bc2.postMessage(e.origin);" +
      "\"], {type: 'text/javascript'}))); </script>";
    window.addEventListener("message", t.step_func(e => {
        assert_equals(e.data.workerMessageOrigin, "null");
        assert_equals(e.data.messageOrigin, "null");
        resolve();
      