converted ConstColorProcessor to SkSL

Bug: skia:
Change-Id: Ic3b18f82c1ab940637fb26dec1cf376dd859b35d
Reviewed-on: https://skia-review.googlesource.com/73720
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
23 files changed