<!DOCTYPE HTML>
<html class="reftest-wait">
<head>

<style>
  body { font-family: sans-serif; }
</style>

<script type="text/javascript">
var loopCount = 0;
var pause = 10; // smaller values make the bug more likely to occur
var src = "data:text/html,iframe 1 <iframe width='100' height='100' src='data:text/html,iframe 2'>";
var start = new Date();

function ap()
{
  document.getElementById("div").style.position = "absolute";
  setTimeout(bp, pause);
}

function bp()
{
  document.getElementById("div").style.position = "";
  setTimeout(cp, pause);
}

function cp()
{
  document.getElementById("iframe").setAttribute("src", src);
  setTimeout(nextIteration, pause);
}

function nextIteration()
{
  var now = new Date();
  loopCount++;
  if (loopCount < 20 && now - start < 5000) {
    ap();
  } else {
    document.body.textContent = "Done";
    document.documentElement.className = '';
  }
}
</script>

</head>

<body onload="ap();"><div id="div"><iframe id="iframe"></iframe></div></body>
</html>