<!DOCTYPE html>

<html>
<head>
    <style>
        .container {
            position: relative;
            height: 200px;
            width: 200px;
            margin: 10px;
        }
        
        .composited {
            -webkit-transform: translateZ(0);
        }
        
        .child {
            position: absolute;
            height: 180px;
            width: 180px;
            margin: 10px;
        }
        
        .masked {
            -webkit-mask: linear-gradient(black, transparent);
        }
        
        .grandchild {
            position: absolute;
            top: 10px;
            left: 10px;
            width: 150px;
            height: 150px;
            background-color: silver;
        }
    </style>
    <script>
        if (window.testRunner)
            testRunner.dumpAsText();

        function dumpLayers()
        {
            var layersResult = document.getElementById('layers');
            if (window.testRunner)
                layersResult.innerText = window.internals.layerTreeAsText(document);
        }

        window.addEventListener('load', dumpLayers, false)
    </script>
</head>
<body>
    <div class="composited container"><div class="masked child"></div></div>
    <div class="composited container"><div class="masked child"><div class="grandchild"></div></div></div>

<pre id="layers">Layer tree goes here in DRT</pre>
</body>
</html>