ladybird/Tests/LibWeb/Text/input/HTML/cross-origin-WindowProxy-postMessage.html

<script src="../include.js"></script>
<iframe id="i"></iframe>
<script>
    asyncTest((done) => {
        window.onmessage = function() {
            println("PASS");
            done();
        };
        i.src = "data:text/html,<script>top.postMessage('done', '*');</sc" + "ript>";
    });
</script>