Re-land "converted OverdrawColorFilter to SkSL"

This reverts commit 2d3cac58fcc8f2d398a421b0341c36479a6ba324.

Bug: skia:
Change-Id: I6607d419f6b30c3e17b52ec5ce67d489bd1ad1dc
Reviewed-on: https://skia-review.googlesource.com/64080
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
22 files changed