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

function boom()
{
  var frame = document.getElementById("f");
  var frameRoot = frame.contentDocument.documentElement;
  document.body.removeChild(frame);
  var i = document.createElementNS("http://www.w3.org/1999/xhtml", "input");
  i.setAttribute("autofocus", "true"); 
  frameRoot.appendChild(i);
}

</script>
</head>

<body onload="boom();"><iframe id="f" src="data:text/html,"></iframe></body>
</html>
