Revert "mark SkRasterPipelineBlitter final"

Revert "mark SkRasterPipelineBlitter final"

This reverts commit 317a1857f80ffc18d591dd6b1ac0988184b1ed2b.

Reason for revert: Valgrind requires reverting ancestor commit.

Original change's description:
> mark SkRasterPipelineBlitter final
>
> This devirtualizes the call from blitAntiH to blitH,
> and makes sure no future self calls will be virtual.
>
> Change-Id: I2a277bbc1450a96e07794791792d59e5f806bde0
> Reviewed-on: https://skia-review.googlesource.com/17418
> Commit-Queue: Mike Klein <mtklein@chromium.org>
> Reviewed-by: Mike Klein <mtklein@chromium.org>
>

TBR=mtklein@chromium.org,herb@google.com,reed@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Change-Id: Ic726fd6b9bf18c397812ecc256353ab4a0a336c5
Reviewed-on: https://skia-review.googlesource.com/17522
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>