Thanks Dan and Matteo for summarising my findings. Glad to see that this has helped, Bogdan!
Regarding my statement of "no need to purge caches": I later found out that this isn't exactly wrong, because purging Moodle caches wouldn't help. Nevertheless, the YUI scripts are aggressively cached by browsers (they are set to never expire). That is usually a good thing, but in this case quite annoying. You will have to advise your (affected) users that they need to clear their Chrome browser cache so that they can obtain the fixed version.