<!DOCTYPE html>
<html class="reftest-wait">
<head>
  <style>
    div#a { margin: 100px 0px 100px 0px;  }
  </style>
  <script>
  function boom()
  {
    var a = document.getElementById("a");
    a.removeChild(a.firstChild);
    document.documentElement.className = "";
  }
  </script>
</head>
<body onload="boom();">
  <div id="a">a</div>
  <div>b</div>
</body>
</html>