I don't think it's failing in all the cases, but for now I think it's safer to just disable it for NVIDIA.
Pull request: https://github.com/WebKit/WebKit/pull/18614
Probably no longer necessary?
Hopefully
Unfortunately I'm getting reports with WebKitGTK 2.46.0: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1082139