People sometimes absentmindedly misspeak. Either that happened and you can politely s/Firefox/browser/ so that the comment reads as a reasonable, even insightful contribution to the discussion, or the comment is utter nonsense and you can feel smug that you’re not as stupid as they must be. Granting the former interpretation is the more charitable option.

You should also understand that “Surely…” doesn’t mean the same thing as “I am sure”. “Surely…” is a plea for sanity.