<!DOCTYPE html>

<html>
<head>
  <style>
    #container {
      position: relative;
      width: 400px;
      height: 100px;
      border: 1px solid  black;
    }
    .box {
      position: absolute;
      width: 100px;
      height: 100px;
      background-color: green;
    }
    .indicator {
      left: 150px;
      top: 0;
      background-color: red;
    }
    #container.moved .software {
      left: 300px;
    }
    #container.moved .hardware {
      transform: translateX(300px);
    }
    .hardware {
      transform-style: preserve-3d;
      transition: transform 300ms linear;
      transform: translateX(0);
    }
   </style>
   <script type="text/javascript">
    'use strict';
    function waitForCompositor() {
      var container = document.getElementById('container');
      return container.animate({opacity: [1, 1]}, 1).ready;
    }

    function testEnded()
    {
      var testDiv = document.getElementById('tester');
      testDiv.style.transitionProperty = 'none';
      testDiv.style.transitionDuration = '0';

      testDiv.style.transform = 'translateX(150px)';
      waitForCompositor().then(() => {
        if (window.testRunner)
          testRunner.notifyDone();
      });
    }
    
    function startTest()
    {
      if (window.testRunner)
        testRunner.waitUntilDone();

      document.body.offsetHeight; // Force style recalc
      document.getElementById('tester').addEventListener('transitionend', testEnded, false);
      document.getElementById('container').className = 'moved';
    }
    
    window.addEventListener('load', startTest, false);
   </script>
</head>
<body>

  <p>At the end of the test the green box should obscure the red box.</p>
  <div id="container">
    <div class="indicator box"></div>
    <div id="tester" class="hardware box"></div>
  </div>

  <div id="result">
  </div>

</body>
</html>