chromium/third_party/blink/web_tests/compositing/culling/filter-occlusion-blur.html

<!DOCTYPE html>
<html><head>
<title>CSS filter blur occlusion test.</title>
<style type="text/css">
  .composited {
    will-change: transform;
  }
  .yellow-parent {
    -webkit-filter: blur(10px);
  }
  .centered {
    width: 200px;
    height: 200px;
    position: absolute;
    left: 100px;
    top: 100px;
  }
</style>
</head>
<body>
<!--
   This test guards against over-culling of the "hidden" yellow box. Since the yellow box is blurred,
   it becomes visible around the outside of the green box.
  -->
<div class="yellow-parent composited" style="position:absolute; left:0; top:0">
  <div class="centered composited" style="background-color: yellow;">
  </div>
</div>
<div class="composited centered" style="background-color: green;">
</div>
</body>
</html>