Implement onFilterColor4f in SkRP.

The SkFilterColorProgram class is now compiled as an empty stub when
SkRP is enabled. This was the last remaining usage of ProgramToSkVM.

Change-Id: I425cf5da8f4723fb36acae076d3a5638562da3e6
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/673718
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
4 files changed