Built 50.0 with cairo-gtk2 backend using it right now but something different with the font rendering in 50.0. For instance there's a weird washed-out effect of the text in this very same text control I'm writing the comment in which comes and goes with the amount of text changing/wrapping etc.
I think I figured it out. Somehow Skia was enabled in Firefox and resetting that seems to have fixed the rendering bug. Given that 51 will turn Skia on by default I hope this will be fixed before the switch.
