Clearly you never tried the original Firefox for Android, which was XUL-based. It was unusable. I remember trying it on my Nexus One, back when that phone was

Clearly you never tried the original Firefox for Android, which was XUL-based. It was unusable. I remember trying it on my Nexus One, back when that phone was hot shit. Constant full-screen checkerboarding. Mozilla literally had to rewrite Firefox for Android and eliminate XUL from the Android version before it became a usable product.