Our server logs tell us that about 20 percent (I don't remember the exact amount, but it's much larger than "non trivial") of our users are Safari users, so this compatibility effort is essential. The saving grace is that the date functions we/I have written, are all in one place and sufficiently abstracted, and that helps me do less work. I had to add two lines of code to fix stuff. The hard part was doing the forensic work via alert() calls.
If I was smarter (and didn't use deprecated date methods), I wouldn't have had to make any edits, and Safari would have been auto-supported. Lesson learned.
Many thanks to those who posted yesterday.