Revert "Remove ability to sample textures in vertex or geometry shaders."

This reverts commit d50d6579d1c00de65b947c0531fa04c043729e49.

Reason for revert: chromes test gles test context is broken. Need to fix that then reland this

Original change's description:
> Remove ability to sample textures in vertex or geometry shaders.
> 
> Bug: skia:
> Change-Id: I69cd07a4bbe4879e855fb4aa6289a049adf4e059
> Reviewed-on: https://skia-review.googlesource.com/c/160021
> Commit-Queue: Greg Daniel <egdaniel@google.com>
> Reviewed-by: Chris Dalton <csmartdalton@google.com>

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

Change-Id: I309dfa5f7118cb8d7280aaf6a88e1df232bd7099
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:
Reviewed-on: https://skia-review.googlesource.com/c/160163
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
21 files changed