chromium/third_party/blink/web_tests/paint/invalidation/compositing/composited-document-element.html

<!DOCTYPE html>

<html>
<head>
  <style>
    html {
      perspective: 1200px;
      background-color: red;
    }
    html.changed {
      background-color: transparent;
    }
    body {
      will-change: transform;
    }
    .box {
      width: 100px;
      height: 100px;
      background-color: blue;
    }
  </style>
  <script>
    if (window.testRunner)
      testRunner.waitUntilDone();

    function doTest()
    {
      window.setTimeout(function() {
        document.documentElement.className = 'changed';
        if (window.testRunner)
          testRunner.notifyDone();
      }, 0);
    }
    window.addEventListener('load', doTest, false);
  </script>
</head>
<body>
  <p>In a pixel test, you should see a plain white background.</p>
</body>
</html>