";
    window.addEventListener("message", t.step_func(e => {
        assert_equals(e.data.workerMessageOrigin, "null");
        assert_equals(e.data.messageOrigin, "null");
        resolve();
      }), {once: true});
    document.body.appendChild(ifr);
    });
}, "Opaque origin should be serialized to \"null\"");
//-->