Revert of Use approximate scratch textures for image filters. (patchset #2 id:20001...

Revert of Use approximate scratch textures for image filters. (patchset #2 id:20001 of https://codereview.chromium.org/679113004/)

Reason for revert:
Continued GM failures

Original issue's description:
> Use approximate scratch textures for image filters.
>
> Committed: https://skia.googlesource.com/skia/+/96c60686eef6fc514feba6136f1b475f71dbf3ec
>
> Committed: https://skia.googlesource.com/skia/+/50a140563c5960acb2479d2be7c437d146963b3f

TBR=senorblanco@google.com,senorblanco@chromium.org,bsalomon@google.com
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/681183002