LayoutTests/imported/blink/http/tests/misc/resources/reentrant-beforeunload-helper.html - WebKit - Git at Google

 <html>
 <body>
 <script>
 window.onbeforeunload = function() {
   window.close();
   return "This should only appear once.";
 }
 </script>
 </body>
 </html>
	<html>
	<body>
	<script>
	window.onbeforeunload = function() {
	window.close();
	return "This should only appear once.";
	}
	</script>
	</body>
	</html>