third_party/WebKit/LayoutTests/external/wpt/service-workers/service-worker/resources/claim-worker-fetch-iframe.html - chromium/src - Git at Google

 <!doctype html>
 <script>
 var worker = new Worker('./claim-worker-fetch-worker.js');

 function fetch_in_worker(url) {
   return new Promise((resolve) => {
     worker.onmessage = (event) => {
       resolve(event.data);
     };
     worker.postMessage(url);
   });
 }
 </script>
	<!doctype html>
	<script>
	var worker = new Worker('./claim-worker-fetch-worker.js');

	function fetch_in_worker(url) {
	return new Promise((resolve) => {
	worker.onmessage = (event) => {
	resolve(event.data);
	};
	worker.postMessage(url);
	});
	}
	</script>