Revert "[graphite] Rasterize SmallPathAtlas paths to the Plot backing store."

This reverts commit e90e38d308f6ccdd58d12f9fcc5173663ac853d8.

Reason for revert: SmallPathAtlas blocking Chrome roll.
https://screenshot.googleplex.com/B9PiA8gokN5hXBo

Original change's description:
> [graphite] Rasterize SmallPathAtlas paths to the Plot backing store.
>
> Currently in the SmallPathAtlas we rasterize to a separate
> SkAutoPixmapStorage and then copy that data to the DrawAtlas via
> addToAtlas(). This CL changes that to request space in the DrawAtlas,
> and then sets up the SkAutoPixmapStorage to point to the backing
> store for the Plot the path is cached in. Finally we use that for our
> rasterization step. All of this avoids that unnecessary copy.
>
> Bug: b/294378744
> Change-Id: Ic47626da13df8c5ed0f5e1449ae0424620639027
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/820699
> Commit-Queue: Jim Van Verth <jvanverth@google.com>
> Reviewed-by: Michael Ludwig <michaelludwig@google.com>

Bug: b/294378744
Change-Id: I9baa5a3c6f8df04982b3264cd1d89cee5a0c5c3c
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/820917
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Auto-Submit: John Stiles <johnstiles@google.com>
5 files changed