Coalesce adjacent push_zeros ops.

It's more efficient for us to use large ops that do a lot of work,
versus multiple small ops that do less.

Change-Id: Ia065ffda08e706f8fedd59472ea272581060ecf6
Bug: skia:13676
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/627618
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
2 files changed