Revert "Switch SkPaint's color to SkColor4f"

This reverts commit ee87c8629cba96c2426ebbc1905c241af52f9ef0.

Reason for revert: Android tests.

Original change's description:
> Switch SkPaint's color to SkColor4f
> 
> Change-Id: Ic2b83a05739720013a7c30ec014df0747b3f99a5
> Reviewed-on: https://skia-review.googlesource.com/149229
> Commit-Queue: Brian Osman <brianosman@google.com>
> Reviewed-by: Mike Klein <mtklein@google.com>

TBR=djsollen@google.com,mtklein@google.com,brianosman@google.com,reed@google.com

Change-Id: I85efd020598d70cbfb90c4f4af7d33482a3d7280
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/151544
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
9 files changed