I've seen this too but don't have any Mac users (except
myself, at home).
You should report this to Adobe as a "bug." Much has changed
for all the Mac versions of browsers since this code was written.
All output code needs to be reviewed before the next RH release.
Meanwhile, if you come up with a safe way to fix this, you
could save and keep a modified version of whutils.js to substitute
after generating any WebHelp. If we're lucky, we might find that
the source file in the RH application folder is identical to the
output version, so you could nip this problem in the bud.
Good luck,
Harvey