That was your first mistake - why put puffy bloated FF on a sleak Android Chrome powered phone? Even for testing purposes? You're talking such a minimal installed base it's a massive waste of time at this point.
Really I'm just trying to get a handle on whether Adsense is being displayed or not in Mobile browsers (I have also installed the various Operas etc).
I have always taken the view that my sites should work in all browsers and resolutions (or at least a broader section than most aim for), so just doing due diligence.