Revert of Move DstCopy on gpu into the GrXferProcessor. (patchset #11 id:200001 of...

Revert of Move DstCopy on gpu into the GrXferProcessor. (patchset #11 id:200001 of https://codereview.chromium.org/885923002/)

Reason for revert:
Testing to see if reverting fixes 10.9 bots.

Original issue's description:
> Move DstCopy on gpu into the GrXferProcessor.
>
> BUG=skia:
>
> Committed: https://skia.googlesource.com/skia/+/74a11753604768bf461b80cabb66060e8564d82c
>
> Committed: https://skia.googlesource.com/skia/+/5e1378d0e075a323144ba14e0a4cbcca35eccc69

TBR=joshualitt@google.com,egdaniel@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Review URL: https://codereview.chromium.org/901663007