<div style="display: table-cell; vertical-align: bottom; width: 100px; height: 100px; overflow: hidden; background-color: red;">
    <div id="target" style="width: 100px; height: 50px; background-color: green;"></div>
</div>
<script>
    if (window.testRunner)
        testRunner.waitUntilDone();

    setTimeout(function()
        {
            document.getElementById("target").style.height = "100px";
            if (window.testRunner)
                testRunner.notifyDone();
        },
     0);
</script>