The problem appears to bigger than just this, though. After experiencing the same issue on mac, I replaced the file you spoke of which, while it allows me to add client validation with the "required" attribute, it actually does not do anything in validation.
In fact, if I add a "required' validation, it makes the entire client validation not do anything at all including that date reformatting, etc. on other items.
I know the fix was to replace the JS file... do we, perhaps, also need a new HTM file to accompany it?
Thanks and best regards,