Make asFragmentProcessor entry point only take a GrRecordingContext

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: I48a5667b1ca31d5648571083fcda76564fae939b
Reviewed-on: https://skia-review.googlesource.com/c/192687
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
25 files changed