<!DOCTYPE html>
<head>
<script>

function boom()
{
  var b = document.createElementNS("http://www.w3.org/1999/xhtml", "div");
  b.style.position = "absolute";
  document.getElementById("a").appendChild(b);
}

</script>
</head>

<body onload="boom();"><div id="a" style="display: -moz-inline-stack; position: relative">x</div></body>
</html>