<!DOCTYPE html>
<html>
<head>
<script>

var f1, f2;

function b1()
{
  f1 = document.getElementById("f1");
  f2 = document.getElementById("f2");
  f1.contentWindow.document.write("11");
  f1.contentWindow.history.back();
  setTimeout(b2, 0);
}

function b2()
{
  f2.contentWindow.history.forward();
  f2.contentWindow.location.reload();
  f1.remove();
}

</script>


</script>
</head>

<body onload="setTimeout(b1, 0);">

<iframe id="f1" src="data:text/html,1"></iframe>
<iframe id="f2" src="data:text/html,2"></iframe>

</body>
</html>
