Make SkColor4f <-> SkColor skip sRGB conversion

This lets us remove the old S32 functions, and fix a couple bugs.
I think this is a good first step to using SkColor4f for paint colors.

Bug: skia:
Change-Id: I0337c2b6db29b73c2f682f85b9cf68c985de7cce
Reviewed-on: https://skia-review.googlesource.com/147205
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
9 files changed