<!DOCTYPE html>

<html>
<head>
    <style>
        body {
            margin: 100px;
            height: 1500px;
            background-attachment: fixed;
        }
        
        .test {
            height: 400px;
            width: 600px;
            background-color: rgba(0, 0, 0, 0.5);
            border: 20px solid orange;
        }
        
        #layers {
            opacity: 0;
        }
    </style>
    <script>
    if (window.testRunner)
        testRunner.dumpAsText(true);
    
    function doTest()
    {
        window.scrollTo(0, 200);

        if (window.internals)
            document.getElementById('layers').innerText = internals.layerTreeAsText(document, internals.LAYER_TREE_INCLUDES_TILE_CACHES);
    }
    
    window.addEventListener('load', doTest, false);
    </script>
</head>
<body>

    <div class="test"></div>
<pre id="layers"></pre>
</body>
</html>