WebRender won't support GDI fonts so we need to figure out what to do with the users that are currently using them. This should help give us better diagnostics on what's going wrong.

WebRender won't support GDI fonts so we need to figure out what to do
with the users that are currently using them. This should help give us
better diagnostics on what's going wrong.

gfxCriticalError only crashes on Nightly and Beta builds

https://hg.mozilla.org/mozilla-central/rev/7980da78f422

This crash doesn't seem to be getting hit and we're still getting failures https://sql.telemetry.mozilla.org/queries/69184/source

I wonder if Factory::GetDWriteSystemFonts is returning null. If we leave out the possibility that the factory itself failed to initialize for now, and assume it is non-null, then the remaining possibility, however unlikely, would be that mDWriteFactory->GetSystemFontCollection() is returning success and a null font collection at the same time. Maybe it's worth adding a check for null systemFonts and see what we can catch...