<!DOCTYPE html>
<html>
<head>
    <style>
        .container {
            position: relative;
            margin: 20px;
            width: 300px;
            height: 300px;
            border: 1px solid black;
        }
        .box {
            position: absolute;
            left: 50px;
            top: 50px;
            z-index: 0;
            width: 200px;
            height: 200px;
        }
        .middle {
            background-color: red;
        }
        .child {
            background-color: green;
            top: 0;
            left: 0;
        }
        .composited {
            transform: translateZ(0);
        }
    </style>
    <script>
        if (window.testRunner)
            testRunner.waitUntilDone();

        window.addEventListener('load', () => {
            requestAnimationFrame(() => {
                document.getElementById('target').classList.remove('composited');
                if (window.testRunner)
                    testRunner.notifyDone();
            });
        }, false);
    </script>
</head>
<body>
    <div class="composited container">
        <div id="target" class="middle composited box">
            <div class="child composited box"></div>
        </div>
    </div>
</body>
</html>