<html>
<body onload="test();">
<script>
function test() {
  var status;
  try {
    var d = frames[0].document.open();
    status = "Allowed";
    d.close();
  } catch (e) {
    status = "Disallowed";
  }
  document.title = status;
}
</script>
<div id=result></div>
<iframe src="data:text/html,"></iframe>
</body>
</html>