Created attachment 568810 [details]
testcase (crashes Firefox when loaded)
Linux-only, I think.
Created attachment 568811 [details]
Created attachment 568822 [details] [diff] [review]
NULL check our created surface
Untransformed size is 40k wide, so creating the surface fails.
Don't think there's much else we can do here except fail to paint the layer.
To save time when doing merges, please could you use the 'assign bug to me' feature when attaching patches. Thanks :-)