third_party/WebKit/LayoutTests/compositing/overflow/empty-composited-child-of-border-radius-ancestor.html

<style>
.outermost {
  border: 4px solid #000;
  border-radius: 40px;
  width: 200px;
  height: 200px;
  overflow: hidden;
}

.inner {
  width: 200px;
  height: 200px;
  position: relative;
  left: 50px;
  top: 50px;
  will-change: transform;
}
</style>

<div class="outermost">
  <div class="inner">
  </div>
</div>