<html>
<style>
    .test {
        width: 300px;
        margin: 10px;
        padding: 10px;
        border: 1px solid black;
    }

    canvas, iframe, img {
        width: 200px;
        height: 100px;
        border: 5px solid gray;
        border-top-left-radius: 10px;
        touch-action: none;
    }
</style>
<script>
    window.onload = function () {
        if (window.testRunner)
            testRunner.dumpAsText();
        if (window.internals)
            results.innerText = internals.layerTreeAsText(document, internals.LAYER_TREE_INCLUDES_EVENT_REGION | internals.LAYER_TREE_INCLUDES_ROOT_LAYER_PROPERTIES);
    }
</script>
<body>
<div class="test">
    <canvas></canvas>
</div>
<div class="test">
    <iframe></iframe>
</div>
<div class="test">
    <img>
</div>
<pre id="results"></pre>
</body>
</html>