chromium/src/third_party/blink/web_tests/fast/events/resources/message-port-gc-closed-cloned-iframe.html - manifest_repos/chromium_src - Git at Google

 <!DOCTYPE html>
 <script>
 window.onmessage = function(evt) {
     var port = evt.ports[0];
     port.start();
     port.postMessage("startedAndClosed");
     port.close();
 }
 </script>
	<!DOCTYPE html>
	<script>
	window.onmessage = function(evt) {
	var port = evt.ports[0];
	port.start();
	port.postMessage("startedAndClosed");
	port.close();
	}
	</script>