Switched SymbolTable.fErrorReporter over to .fContext

Holding on to the ErrorReporter directly could leave it talking to the
wrong reporter if the context was updated.

Change-Id: I60a343f0c5d296c4e847bb8cf97ecce3136579f6
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/442796
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
6 files changed