Make asFragmentProcessor entry point only take a GrRecordingContext (take 2)

This is split out of: https://skia-review.googlesource.com/c/skia/+/192032 (Switch FP creation over to GrRecordingContext)

TBR=bsalomon@google.com

Change-Id: Iebe8dce00abf09485717f59daae1bfeb8ba6d5bc
Reviewed-on: https://skia-review.googlesource.com/c/193160
Reviewed-by: Robert Phillips <robertphillips@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
25 files changed