stage version of vertices

This CL, just to limit its size/complexity, only handles
colors but not textures. Future CLs will cover everything.

Performance is pretty exciting. Its faster than the old code-path,
and when we fix a bug in pathutils to preserve opaqueness, it gets
a lot faster (8 -> 5)

Bug: skia:
Change-Id: I4113060e25fe25fe4e6a0ea59bd4fa5e33abc668
Reviewed-on: https://skia-review.googlesource.com/17276
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Mike Klein <mtklein@chromium.org>
Reviewed-by: Florin Malita <fmalita@chromium.org>
7 files changed