LayoutTests/fast/forms/menulist-selection-reset.html

<select id="select">
    <option>FAIL</option>
    <option>PASS</option>
    <option selected="true">Did not run</option>
</select>
<p id="result">
</p>
<script>
    if (window.layoutTestController)
        layoutTestController.dumpAsText();

    select.selectedIndex = 1;
    result.innerText = select.selectedIndex == 1 ? "PASS" : "FAIL";
</script>