Revert "Add support for matrix == and != in Metal shaders."

This reverts commit c50185718830a6220b28be885cebd3959a0f0698.

Reason for revert: breaking many bots

Original change's description:
> Add support for matrix == and != in Metal shaders.
>
> We need to polyfill an operator== and != when these are first
> encountered in the code.
>
> Change-Id: I539c838ee1871bcb0c4b66abb8a4a0f91146cd4f
> Bug: skia:11306
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/368496
> Auto-Submit: John Stiles <johnstiles@google.com>
> Reviewed-by: Brian Osman <brianosman@google.com>

TBR=brianosman@google.com,ethannicholas@google.com,johnstiles@google.com

Change-Id: Id583109a0d167c2c58a57644b14cd5f49d670737
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:11306
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/368801
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
8 files changed