Revert of Change SkShader;asFragmentProcessor signature to no longer take skpaint...

Revert of Change SkShader;asFragmentProcessor signature to no longer take skpaint\grcolor* (patchset #8 id:140001 of https://codereview.chromium.org/1316513002/ )

Reason for revert:
Primary suspect in failing DEPS rolls:
* https://codereview.chromium.org/1315753006
* https://codereview.chromium.org/1308323006
* https://codereview.chromium.org/1320903004

Primary suspect because the failing win bots did not fail in https://codereview.chromium.org/1315753005

Original issue's description:
> Change SkShader;asFragmentProcessor signature to no longer take skpaint\grcolor*
>
> Committed: https://skia.googlesource.com/skia/+/ecfdc251be71f3d634e76afdd6375bf55fc061aa

TBR=joshualitt@google.com,wangyix@google.com,robertphillips@google.com,bsalomon@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/1313573005