<span id="target" style="padding-bottom: 100px; background-color: red; padding-left: 100px; position: relative;"></span>
<script>
    document.getElementById("target").addEventListener("click", function(event) {
        event.target.style.backgroundColor = "green";
        document.body.appendChild(document.createTextNode("PASS"));
    });

    document.body.offsetTop;
    if (window.testRunner) {
        testRunner.dumpAsText();
        eventSender.mouseMoveTo(50, 50);
        eventSender.mouseDown();
        eventSender.mouseUp();
    }
</script>