It looks mootools-1.2.5 have an issue on IE 8 and chrome when you use:
$(document).addEvent('domready',function(){alert("test");});
but their home page says: “MooTools is compatible and fully tested with Safari, Internet Explorer 6+, Firefox, Opera, and Chrome.”
you should add the domready event to window, not document. that’s all. reading the manual helps – even the tag wiki here has this very example:
https://stackoverflow.com/tags/mootools/info