<!DOCTYPE html>
<html>
<script>
    function startTest() {
        if (window.testRunner) {
            testRunner.waitUntilDone();
            testRunner.setBackingScaleFactor(2, finishTest);
        }
    }
    
    function finishTest() {
        setTimeout(function() { testRunner.notifyDone() }, 0);
    }
</script>
</head>
<body onload="startTest();">
<div style='position: absolute; left: 5px; top: 10px; width: 50px; height: 50px; background-color: green'>
</div>
</body>
</html>