workers-in-cross-origin-iframe.html

<!DOCTYPE html>
<title>Construction of Web Workers is deferred</title>
<script src="utils.js"></script>
<body>
<script type="module">

const bc = new PrerenderChannel('test-channel');
const worker = new Worker('worker-post-timeOrigin.js');
worker.onerror = e => bc.postMessage('Fail');
await new Promise(resolve => worker.onmessage = resolve);
bc.postMessage('Success');

</script>
</body>
</html>

chromium/third_party/blink/web_tests/external/wpt/speculation-rules/prerender/resources/workers-in-cross-origin-iframe.html