LayoutTests/http/tests/notifications/resources/request-in-detached-frame-subframe.html

<script>
onmessage = function(msg) {
    let p = parent;
    p.testFrame.remove();
    p.shouldBeEqualToString("Notification.permission", "default");
    Notification.requestPermission((result) => {
        p.testFailed("Permission handler should not have been called");
    });
}
</script>