Revert "fix ubsan warning"

This reverts commit 4d1c5d676eb32ed304ee4aa410cebbc6467b59c2.

Reason for revert: This one was fine (and fixes ASAN).

Original change's description:
> fix ubsan warning
>
> CQ_INCLUDE_TRYBOTS=skia.primary:Test-Ubuntu-Clang-GCE-CPU-AVX2-x86_64-Debug-ASAN
>
> Change-Id: Ic8c5d95fdb899cb5293b2bc456f61b1637ec3aed
> Reviewed-on: https://skia-review.googlesource.com/17489
> Reviewed-by: Mike Klein <mtklein@chromium.org>
> Commit-Queue: Mike Klein <mtklein@chromium.org>
>

TBR=mtklein@chromium.org,herb@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
CQ_INCLUDE_TRYBOTS=skia.primary:Test-Ubuntu-Clang-GCE-CPU-AVX2-x86_64-Debug-ASAN

Change-Id: Id51bf64617f9bf11d80e6163783d7101fef9c5e2
Reviewed-on: https://skia-review.googlesource.com/17525
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>