Gradient stages cleanup

Hoist the matrix setup into SkGradientShaderBase.

Drop the bool return for adjustMatrixAndAppendStages(), and rename to
appendGradientStages().

Change-Id: Iad412f638f86223e5af46a7d3dea6f768f52bcad
Reviewed-on: https://skia-review.googlesource.com/26427
Commit-Queue: Florin Malita <fmalita@chromium.org>
Reviewed-by: Mike Reed <reed@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
10 files changed