<!DOCTYPE html>

<html>
<head>
    <style>
        body {
            height: 2000px;
            width: 1000px;
        }
        
        .fixed {
            position: fixed;
            height: 100px;
            width: 100px;
            background-color: rgba(0, 0, 0, 0.5);
        }
        
        .top, .bottom {
            left: 0;
            width: 100%;
        }
        
        .left, .right {
            top: 200px;
        }
        
        .top {
            top: 0;
        }
        
        .bottom {
            bottom: 0;
        }
        .left {
            left: 0;
        }
        .right {
            right: 0;
        }
    </style>
    <script>
        
        if (window.testRunner) {
            testRunner.dumpAsText();
            testRunner.waitUntilDone();
        }

        if (window.internals) {
            internals.settings.setAcceleratedCompositingForFixedPositionEnabled(true);
            internals.setUseFixedLayout(true);
            internals.setFixedLayoutSize(1000, 2000);
            var scale = 800 / 1000;
            eventSender.scalePageBy(scale, scale);
        }
        
        function doTest()
        {
            window.setTimeout(function() {
                document.getElementById("layerTree").innerText = window.internals.layerTreeAsText(document);
                testRunner.notifyDone();
            }, 0);
        }
        
        window.addEventListener('load', doTest, false);
    </script>
</head>
<body>

<div class="top fixed">
    Top
</div>

<div class="left fixed">
    Left
</div>

<div class="right fixed">
    Right
</div>

<div class="bottom fixed">
    bottom
</div>

<pre id="layerTree"></pre>
</body>
</html>