Bzzzt wrong. Look at the code, it's 98% or so C++. The only parts that are Java are some database access layers and some stuff for multimedia. Way to show yourself as being an idiot for repeating this oft-repeated and incorrect meme.
Second: The language has little to no bearing on the amount of RAM being used. The amount of data being stored (and how it's stored), however, does. Firefox stores a lot of images and such, which, surprise surprise, eat up RAM.
So then you've just effectively nullified your own point since you were blaming the languages on the bloat instead of the crappy programmers.