<!DOCTYPE html>
<html>
<head>
    <style>
        body {
            height: 500px;
        }
        
        .overflowing {
            width: 200px;
            height: 250px;
        }
        
        .contents {
            position: relative;
            z-index: 1;
            height: 400px;
        }
        
        .negative-z {
            position: absolute;
            width: 100px;
            height: 50px;
            z-index: -1;
            border: 1px solid black;
        }

        .composited {
            transform: translateZ(0);
        }
    </style>
    <script>
        if (window.testRunner) {
            testRunner.setRenderTreeDumpOptions(testRunner.RENDER_TREE_SHOW_ALL_LAYERS
                    | testRunner.RENDER_TREE_SHOW_LAYER_NESTING
                    | testRunner.RENDER_TREE_SHOW_COMPOSITED_LAYERS
                    | testRunner.RENDER_TREE_SHOW_OVERFLOW
                    | testRunner.RENDER_TREE_SHOW_SVG_GEOMETRY
                    | testRunner.RENDER_TREE_SHOW_LAYER_FRAGMENTS);
        }
    </script>
</head>
<body>
    <div class="overflowing">
        <div class="contents"></div>
    </div>
    <div class="negative-z composited"></div>
    <div style="height: 200px">
        <svg>
            <rect x="10" y="20" width="100" height="100" fill="blue"/>
        </svg>
    </div>
</body>
</html>