This isn't a definitive answer, just some observations. When I'm at PC I get neither popup ads nor the Firefox notice that it just prevented a popup from opening. I think that pretty well rules out unwanted popups.

Chat comes in a choice of popup or no-popup versions. Some kinds of editing (like status updates) are done in what looks to me just like a popup window. As I recall, you can choose to get a popup notification when a PM or something comes in. None of these look or act anything like the casino ads and other junk that some sites still manage to slip onto my screen occasionally in spite of Firefox.