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<p>This ensures that postMessage called in a callback does not crash.

<pre>FAIL</pre>

<script>
if (window.testRunner) {
    testRunner.dumpAsText();
    testRunner.waitUntilDone();
}

var n = 0;

function finishIfNeeded()
{
    if (++n === 2) {
        document.querySelector('pre').textContent = 'PASS';
        if (window.testRunner)
            testRunner.notifyDone();
    }
}

window.onerror = function() {
    finishIfNeeded();
    return true;
};

onmessage = () => {
    finishIfNeeded();
}

requestAnimationFrame(postMessage);
setTimeout(postMessage);

if (window.testRunner)
    testRunner.displayAndTrackRepaints();

</script>
</body>
</html>