LayoutTests/compositing/shared-backing/partial-compositing-update2.html

<!DOCTYPE html>
<html>
<head>
    <title></title>
    <style>
        
        .container {
            position: relative;
            margin: 20px;
            width: 300px;
            height: 300px;
            border: 1px solid black;
        }
        
        .composited {
            transform: translateZ(0);
        }
        
        .relative {
            position: relative;
            top: -20px;
            margin: 10px;
            padding: 10px;
            border: 2px solid orange;
        }
        
        .clipping {
            overflow: hidden;
            height: 200px;
        }
        
        .trigger {
            margin: 10px;
            height: 50px;
            background-color: silver;
        }
        
        .composited.relative {
            height: 200px;
        }
        
        .absolute {
            position: absolute;
            margin: 10px;
            height: 10px;
            width: 100px;
            background-color: silver;
        }
        
        body.changed .changing {
            width: 120px;
        }
    </style>
    <script>
        if (window.testRunner) {
            testRunner.waitUntilDone();
            testRunner.dumpAsText();
        }

        window.addEventListener('load', () => {
            setTimeout(() => {
                document.body.classList.add('changed');
                if (window.internals)
                    document.getElementById('layers').textContent = internals.layerTreeAsText(document);
                if (window.testRunner)
                    testRunner.notifyDone();
            }, 0);
        }, false);
    </script>
</head>
<body>
    <div class="composited container">
        <div class="composited trigger"></div>
        <div class="relative clipping">
            <div class="relative changing"></div>
            <div class="absolute" style="top: 10px;"></div>
            <div class="absolute" style="top: 30px;"></div>
            <div class="absolute" style="top: 50px;"></div>
        </div>
    </div>
<pre id="layers"></pre>
</body>
</html>