void SkColorFilter::onAppendStages(...)

SkColorFilter::onAppendStages() can't actually fail today.
Let's enforce that.  This means the fallback is now used
only for color filters that have not implemented onAppendStages().

Change-Id: Ica3939685694f6186727766b54914b9ba05ca68c
Reviewed-on: https://skia-review.googlesource.com/16231
Reviewed-by: Matt Sarett <msarett@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
11 files changed