LayoutTests/http/tests/misc/resources/iframe-shadow-realm-subframe.html - WebKit - Git at Google

 <body>
     <script>
      onload = async function ()
      {
          var sr = new ShadowRealm();
          var bloop_val = await sr.importValue("./iframe-shadow-realm.js", "bloop");
          window.parent.postMessage(bloop_val, "*");
      }
     </script>
 </body>
	<body>
	<script>
	onload = async function ()
	{
	var sr = new ShadowRealm();
	var bloop_val = await sr.importValue("./iframe-shadow-realm.js", "bloop");
	window.parent.postMessage(bloop_val, "*");
	}
	</script>
	</body>