Remove texel buffer support.

Change-Id: Ia6f21afe714208979a5bc384e436b28ea2b9a297
Reviewed-on: https://skia-review.googlesource.com/141051
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
45 files changed