Revert "use blitMask for left/right edges in blur-nine"

This reverts commit 3fe44544c93759e7791ee0df3e5d172cb0f268b6.

Reason for revert: I believe this is the cause of the layout test regressions in crbug.com/737714

Bug: 737714

Original change's description:
> use blitMask for left/right edges in blur-nine
> 
> Seems about same speed for legacy blitter, but much faster for raster-pipeline
> 
> Bug: skia:
> Change-Id: I19be307c01a199e2477e045fb8c2cca7784564a5
> Reviewed-on: https://skia-review.googlesource.com/20967
> Commit-Queue: Mike Reed <reed@google.com>
> Reviewed-by: Mike Klein <mtklein@chromium.org>

TBR=mtklein@chromium.org,mtklein@google.com,fmalita@chromium.org,reed@google.com

Change-Id: Id7be3ff779191175d91ebd51c7d275fd1104ae0d
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:
Reviewed-on: https://skia-review.googlesource.com/21182
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
1 file changed