Half float vertex colors (when necessary) in small path renderer

Bug: skia:
Change-Id: I34fa12e8d7dbf003d4776df779967dd273228502
Reviewed-on: https://skia-review.googlesource.com/c/174302
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
8 files changed