Revert "Add new method for storing DrawOpAtlas texture index."

This reverts commit c8b2e615400fe43b74dbbd2d7167bb97bd032f87.

Reason for revert: Seeing multitexture failures on Gold

Original change's description:
> Add new method for storing DrawOpAtlas texture index.
> 
> Storing the texture index in the lower bit of each texture coordinate
> seems to have issues on certain iOS devices. Rather than do that, we
> use the sign of the texture coordinate to act as our storage bit.
> To manage encoding 0 we map [0, N] to [-1, -N-1] to represent a bit.
> 
> Change-Id: Ic588ee92cf858915a1833cf482d4b23bd11c1000
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/263561
> Commit-Queue: Jim Van Verth <jvanverth@google.com>
> Reviewed-by: Brian Osman <brianosman@google.com>

TBR=jvanverth@google.com,brianosman@google.com

Change-Id: I9ba28eb800e608fb5ee1ce877b5ab8b5b99db261
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/264421
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
8 files changed