A8 fast path for raster clip masks

When the clip mask is already A8, we don't need to convert explicitly.

Before:

  792.72  clipmask_a8 8888

After:

  560.06  clipmask_a8 8888

BUG=skia:6005

Change-Id: I9a319df9a82edfc9b412787a36f037bbe82c2825
Reviewed-on: https://skia-review.googlesource.com/16420
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Florin Malita <fmalita@chromium.org>
1 file changed