<!DOCTYPE html>
<html>
<style>
    textarea {
        width: 200px;
        height: 200px;
        background: green;
    }
</style>
<script src="../resources/ui-helper.js"></script>
<body>
<textarea></textarea>
<pre id="results"></pre>
<script>
if (window.testRunner) {
    testRunner.waitUntilDone();
    testRunner.dumpAsText();
}

window.onload = async function () {
    document.querySelector("textarea").focus();
    await UIHelper.renderingUpdate();

    if (window.internals)
       results.textContent = internals.layerTreeAsText(document, internals.LAYER_TREE_INCLUDES_EVENT_REGION | internals.LAYER_TREE_INCLUDES_ROOT_LAYER_PROPERTIES);
    if (window.testRunner)
        testRunner.notifyDone();
};
</script>
</body>
</html>