child-transform-layer-with-child-clipping-layer.html

<!DOCTYPE HTML>
<!--
  This test creates a situation where introduce two bookkeeping layers to apply
  the perspective and the clip. It ensures that these layers are positioned
  correctly. If the test is not working the red div with class "perspective"
  will be exposed.
-->
<style>
.perspective {
    background: red;
    width: 100px;
    height: 100px;
    overflow: hidden;
    box-shadow: 0 0 100px 100px rgba(10, 10, 10, 0.0);
    perspective: 100px;  
}
.cover {
    background: green;
    height: 500px;
    will-change: transform;
}
</style>
<div class="perspective">
    <div class="cover"></div>
</div>

chromium/third_party/blink/web_tests/compositing/child-transform-layer-with-child-clipping-layer.html