Revert "Revert "Add private grpixelconfigs for alpha_8 and alpha_half""

This reverts commit 0fb6db4be6e30777cc5c87f1b601e8c4aacff2b1.

Reason for revert: fixed bug

Original change's description:
> Revert "Add private grpixelconfigs for alpha_8 and alpha_half"
>
> This reverts commit 33d17cbb003975fff895954435183756f9893c17.
>
> Reason for revert: broke intel bots
>
> Original change's description:
> > Add private grpixelconfigs for alpha_8 and alpha_half
> >
> > Bug: skia:
> > Change-Id: I5191b6e045aea2a5af2b305b5972ad1e638a7ace
> > Reviewed-on: https://skia-review.googlesource.com/71763
> > Reviewed-by: Brian Salomon <bsalomon@google.com>
> > Commit-Queue: Greg Daniel <egdaniel@google.com>
>
> TBR=egdaniel@google.com,bsalomon@google.com
>
> Change-Id: I6fff9241f7878f1ec7fad2663df9922c9cd8f628
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Bug: skia:
> Reviewed-on: https://skia-review.googlesource.com/72180
> Reviewed-by: Greg Daniel <egdaniel@google.com>
> Commit-Queue: Greg Daniel <egdaniel@google.com>

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

Change-Id: Ie028961ecbf5934c53cb859e019e548935b3af79
Reviewed-on: https://skia-review.googlesource.com/72241
Commit-Queue: Greg Daniel <egdaniel@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
14 files changed