Revert "Reuse GrTexture instances when the same GrBackendTexture is used to"

This reverts commit 559c617137517ece202d0f7cdb6b1cd0a715cf2e.

Reason for revert: breaking things

Original change's description:
> Reuse GrTexture instances when the same GrBackendTexture is used to
> repeatedly fulfill a promise SkImage.
> 
> Bug: skia:8613
> 
> Change-Id: I35c76435d630d2daa034e0c3efb59666bfd6882a
> Reviewed-on: https://skia-review.googlesource.com/c/175820
> Commit-Queue: Brian Salomon <bsalomon@google.com>
> Reviewed-by: Robert Phillips <robertphillips@google.com>

TBR=bsalomon@google.com,robertphillips@google.com

Change-Id: I7548809945d0a875fdb9387398bbc45e733c0846
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:8613
Reviewed-on: https://skia-review.googlesource.com/c/182960
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
20 files changed