<!DOCTYPE html> <!-- webkit-test-runner [ internal:AsyncOverflowScrollingEnabled=true ] -->
<html>
<head>
    <style>
        .scroller {
            position: absolute;
            z-index: 0;
            margin: 20px;
            width: 300px;
            height: 300px;
            border: 1px solid black;
            overflow: hidden;
        }
        .scroller.scrollable {
            overflow-y: scroll;
        }
        .contents {
            height: 2000px;
        }
        .negative {
            position: absolute;
            top: 0;
            left: 0;
            z-index: -1;
            padding: 20px;
            background-color: gray;
        }
        .box {
            width: 200px;
            height: 200px;
        }
        .composited {
            width: 20px;
            height: 20px;
            transform: translateZ(0);
            background-color: silver;
        }
    </style>
    <script>
        if (window.testRunner)
            testRunner.waitUntilDone();

        window.addEventListener('load', () => {
            setTimeout(() => {
                document.getElementById('target').classList.add('scrollable');
                if (window.testRunner)
                    testRunner.notifyDone();
            }, 0);
        }, false);
    </script>
</head>
<body>
    <div id="target" class="scroller">
        <div class="negative"></div>
        <div class="contents">
            <div class="composited box"></div>
            <div class="box" style="background-color: green"></div>
        </div>
    </div>
</body>
</html>