bug in HTML_AJAX from Firefox 5

<html>
<head>
<script type="text/javascript">
<?php
include 'data/HTML_AJAX/js/util.js';
?>
function init()
{
    HTML_AJAX_Util.setInnerHTML(
            "target",
            "<script type='text/javascript'>"+
                "alert('Hello world!');</"+
            "script>",
            "append"
    );
}
</script>
</head>
<body onload="init();"">
<div id="target"></div>
</body>
</html>