Are you talking about these guides?
Gee Whiz, you guys are fast. I was hoping I could get that post off before I looked like a complete Gomer.
I'm jumping back and forth from one computer to another and it turns out that I didn't have a PDF reader installed in FF 19.
Please don't tell anyone, OK.
It looks like that has been in FF for a while, at least according to the this article (Back in FF15):
Whoever came up with the phrase "There is no such thing as a stupid question" obviously never had the internet.