redirect.sub.html
<!DOCTYPE html>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="./support/helper.js"></script>
<body>
<script>
async_test(t => {
var i = document.createElement('iframe');
i.src = "./support/redirect.py?value=DENY&url=/x-frame-options/support/xfo.py%3Fvalue%3DALLOWALL";
wait_for_message_from(i, t)
.then(t.step_func_done(e => {
assert_equals(e.data, "Loaded");
i.remove();
}));
document.body.appendChild(i);
}, "XFO on redirect responses is ignored.");
</script>