ancestor-clipping-mask-non-composited-scroll.html

<!doctype HTML>
<div id=target style="width: 200px; height: 200px; overflow-y: scroll; border-radius: 5px">
  <div style="width: 100px; height: 100px; background: lightblue; will-change: transform;"></div>
  <div style="width: 100px; height: 300px;"></div>
</div>
<script>
if (window.testRunner)
  window.testRunner.waitUntilDone();
onload = function() {
  requestAnimationFrame(() =>
    requestAnimationFrame(() => {
      target.scrollBy(0, 50);
      if (window.testRunner)
        window.testRunner.notifyDone();
    }));
}
</script>

chromium/third_party/blink/web_tests/compositing/masks/ancestor-clipping-mask-non-composited-scroll.html