chromium/third_party/blink/web_tests/fast/frames/resources/detach-frame-nested-subframe.html

<!DOCTYPE html>
<html>
<script>
function createXHR(url) {
    var x = new XMLHttpRequest();
    x.onabort = window.parent.removeFrame;
    x.open('GET', url);
    return x;
}

function runTest () {
    var x1 = createXHR('resources/not-there.txt');
    var x2 = createXHR('resources/not-there-either.txt');
    x1.send();
    x2.send();
}
window.onload = runTest;
</script>
</html>