third_party/WebKit/LayoutTests/http/tests/serviceworker/resources/reply-to-message.html - chromium/src - Git at Google

 <!DOCTYPE html>
 <script>
 window.addEventListener('message', event => {
     var port = event.ports[0];
     port.postMessage(event.data);
   });
 </script>
	<!DOCTYPE html>
	<script>
	window.addEventListener('message', event => {
	var port = event.ports[0];
	port.postMessage(event.data);
	});
	</script>