Revert "Add Short4 vertex attributes, and benchmark them as 4.12 colors"

This reverts commit d2ca0473f67fda52ceea7a5b2162aca5c44ce0bb.

Reason for revert: Various bots failing.

Original change's description:
> Add Short4 vertex attributes, and benchmark them as 4.12 colors
> 
> This is likely our best widely portable option for encoding wide gamut
> colors that doesnt sacrifice too much performance. The benchmark uses
> them as we're likely to do: 4.12 fixed point, in the destination color
> space. We're using SINT vertex attributes for simplicity, so the encode
> and decode are simple multiply/divide by 4096.
> 
> Bug: skia:
> Change-Id: I9b544f3e187b775d81f83dc9dd44611570ad33c2
> Reviewed-on: https://skia-review.googlesource.com/155001
> Reviewed-by: Mike Klein <mtklein@google.com>
> Commit-Queue: Brian Osman <brianosman@google.com>

TBR=mtklein@google.com,bsalomon@google.com,brianosman@google.com

Change-Id: I921e29cf9a121c5752ec7d99a03470b5193afd4a
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:
Reviewed-on: https://skia-review.googlesource.com/154883
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
6 files changed