chromium/src/third_party/blink/web_tests/fast/frames/resources/sandboxed-iframe-form-dynamic-allowed.html - manifest_repos/chromium_src - Git at Google

 <script>
 window.addEventListener("message", function(e) {
     document.getElementById('form').submit();
 }, false);
 </script>
 <body>
 <form id="form" action="javascript:window.top.allowedFormSubmitted();">
     <input name=x value=y type="checkbox" checked="yes"/>
 </form>
 </body>
	<script>
	window.addEventListener("message", function(e) {
	document.getElementById('form').submit();
	}, false);
	</script>
	<body>
	<form id="form" action="javascript:window.top.allowedFormSubmitted();">
	<input name=x value=y type="checkbox" checked="yes"/>
	</form>
	</body>