var _gaq = [['_setAccount', 'UA-XXXXX-X'], ['_trackPageview']];
var _gaq = [ ['_setAccount', 'UA-XXXXX-X'], ['_trackPageview'] ];
Space them out:
var _gaq = [ ['_setAccount', 'UA-XXXXX-X'], ['_trackPageview'] ];
JS doesn’t care about spaces in between the brackets; this will make MODx ignore them.