<html>
<head>
<style>
    body {
        height: 5000px;
        background-color: red;
        overflow: hidden;
    }

    #trigger {
        -webkit-transform:translateZ(0);
    }

    #overlap {
        width: 1000px;
        height: 1000px;
        background-color: green;
        position: fixed;
        left: 0px;
        top: 0px;
    }
</style>
</head>
<script>
    function doTest() {
        if (window.testRunner)
            testRunner.dumpAsText(true);
        window.scrollTo(0, 2000);
        if (window.testRunner)
            testRunner.displayAndTrackRepaints();
        window.scrollTo(0, 1800);
    }
    window.addEventListener("load", doTest, false);
</script>
<body>
    <div id="trigger"></div>
    <div id="overlap"></div>
</body>
</html>