chromium/src/third_party/blink/web_tests/http/tests/navigation/post-with-modifier.html

<div id="container">
<p>You should run this test in Test Runner</p>
<form method="post" action="resources/post-with-modifier.php">
    <input type="hidden" name="a" value="b">
    <input type="submit">
</form>
</div>
<div id="console"></div>
<script>
if (window.testRunner) {
    testRunner.dumpAsText();
    testRunner.setCanOpenWindows(true);
    testRunner.waitUntilDone();

    window.onload = function() {
        var submit = document.querySelector('input[type="submit"]');
        eventSender.dragMode = false;
        eventSender.mouseMoveTo(submit.offsetLeft + 3, submit.offsetTop + 3);
        eventSender.mouseDown(0);
        eventSender.mouseUp(0, ['shiftKey']);
    };
}
</script>