force all colorfilters to implement 4f

high-contrast gms differ at most by 1 bit

Bug: skia:
Change-Id: I1308bd105020ea3cd5a30fd3dd322ed134fb5ed5
Reviewed-on: https://skia-review.googlesource.com/15249
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Mike Klein <mtklein@chromium.org>
Reviewed-by: Florin Malita <fmalita@chromium.org>
11 files changed