Remove SkImageFilter_Base::Context in preference to skif::Context

Change-Id: Ifdc5cafe9ff99ea1b6f7b06be73ac7b1871033e0
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/716756
Auto-Submit: Kevin Lubick <kjlubick@google.com>
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
13 files changed