<!DOCTYPE html>

<html>
<head>
  <style>
    .fixed {
      position: fixed;
      width: 10px;
      height: 10px;
      background-color: silver;
    }
  </style>

  <script type="text/javascript">
    if (window.testRunner) {
      testRunner.dumpAsText();
      testRunner.waitUntilDone();

      window.addEventListener("load", function() {
        window.setTimeout(function() {
          document.getElementById("scrollingTree").innerText = window.internals.scrollingStateTreeAsText();
          testRunner.notifyDone();
        }, 10);
      }, false);
    }
  </script>
</head>

<body>
  <div style="height: 1000px">
    <pre id="scrollingTree"></pre>
  </div>

  <div class="fixed" style="z-index: -1; top: -100px"></div>
  <div class="fixed" style="z-index: -1; top: 0px; left: 1000px"></div>

  <div class="fixed" style="top: 0px; left: 0px"></div>
</body>
</html>