I am working on a fix now. There have been a few changes in the past few weeks that could have caused this. I believe that I have a fix for most of the failures.
Created attachment 46310 [details] Patch
Comment on attachment 46310 [details] Patch r=me \o/
Yay! Thanks Ollie! Fixed with r53103.
Can we close this bug now? Masking and shadows have another bug.
Yes! Sorry, I meant to do that.