<!DOCTYPE html>
<html>
<head>
<style>
.box {
height: 100px;
width: 100px;
margin: 50px;
background-color: blue;
box-shadow: 0 0 20px black;
overflow: hidden;
will-change: transform;
}
.child {
position: relative;
top: -30px;
left: -30px;
width: 300px;
height: 300px;
background-color: silver;
}
</style>
<script type="text/javascript">
if (window.testRunner)
testRunner.dumpAsText();
function doTest() {
if (window.testRunner && window.internals)
document.getElementById('layertree').innerText = internals.layerTreeAsText(document);
}
window.addEventListener('load', doTest, false);
</script>
</head>
<body>
<div class="box">
<div class="child">
</div>
</div>
<pre id="layertree"></pre>
</body>
</html>