<!DOCTYPE html>
<html>
<head>
<script type="text/javascript">
function boom()
{
var s = document.createElement("STYLE");
var t = document.createTextNode("\uDB00x"); // a high surrogate followed by 'x'
document.documentElement.appendChild(s);
s.appendChild(t);
}
</script>
</head>
<body onload="boom();">
</body>
</html>