chromium/third_party/blink/web_tests/compositing/squashing/squashing-layer-control-clip.html

<!DOCTYPE html>
<style>
  ::-webkit-inner-spin-button {
    opacity: 0.9;
    will-change: transform;
  }
</style>
<!-- The spin button establishes a squashing layer. The control clip (established
     by the input) over the spin button should be skipped in the layer state of
     the squashing layer because it doesn't apply on the squashed layers. -->
<input type="number" style="width: 30px; height: 30px">
<div id="target" style="position: absolute; top: 0; width: 100px; height: 100px; background: green"></div>