Removed ErrorHandler pointers from CodeGenerators

These pointers were largely redundant because the CodeGenerators also
had access to a Context, and in a future CL Context becomes the source
of truth regarding the current ErrorHandler, so they are potentially
dangerous.

Change-Id: Ie4175fcb3e1f586baaa42d16c05058aea78532f0
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/439164
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
8 files changed