add support for ctype=SkPMColor4f to GrSkSLFP

Bug: skia:
Change-Id: I222cd0afad2c5226f8ccdec5c5c989c56671c2ff
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/228057
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
1 file changed