Revert "DeferredTextureImageData low-bit-depth/dithering support"

This reverts commit 2c075e749d1f33dea06ad2710e15c9a1d60ebced.

Reason for revert: Breaking tests. e.g.: https://chromium-swarm.appspot.com/task?id=369dc44f62ce9510&refresh=10

Original change's description:
> DeferredTextureImageData low-bit-depth/dithering support
> 
> Cause DeferredTextureImageData functionality to support low bit depth
> (4444, 565) image formats (with dithering).
> 
> Bug: 720105
> Change-Id: Ie3b5768ebc393d9b0a5322461c722bf37c80b791
> Reviewed-on: https://skia-review.googlesource.com/18945
> Reviewed-by: Brian Salomon <bsalomon@google.com>
> Commit-Queue: Eric Karl <ericrk@chromium.org>

TBR=bsalomon@google.com,ericrk@chromium.org
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 720105

Change-Id: I07aec722425efc62bc54f82cee9a19a9bf339f7b
Reviewed-on: https://skia-review.googlesource.com/19039
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
6 files changed