<html xmlns="http://www.w3.org/1999/xhtml" xmlns:math="http://www.w3.org/1998/Math/MathML">
<head>
<script>

function boom()
{
  var textNode = document.createTextNode("a");
  document.getElementById("mathy").appendChild(textNode);
  document.documentElement.offsetHeight;
  textNode.data = "bc";
}

</script>
</head>

<body onload="boom();">

<table><span></span><math:mrow id="mathy" /></table>

</body>
</html>