Revert "Revert "Revert "Add multitexture support to text and path shaders"""

This reverts commit 6c251d24cf90a5c4c091bb7b7373e72705f716d2.

Reason for revert: crashes Fuchsia.

Original change's description:
> Revert "Revert "Add multitexture support to text and path shaders""
> 
> This does not add additional textures to the atlases, just adds the
> ability to access those textures in the shaders.
> 
> Bug: skia:3550
> Change-Id: I552e2c2e4713a5ea68801fdb8e3bab3867e77988
> Reviewed-on: https://skia-review.googlesource.com/44261
> Reviewed-by: Robert Phillips <robertphillips@google.com>

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

Change-Id: I25cc5f11a1fa76ca7b2cf24920ae3a2a15aac723
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:3550
Reviewed-on: https://skia-review.googlesource.com/44540
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
5 files changed