Revert of Refactor parsing and storage of SkGammas (patchset #8 id:280001 of https...

Revert of Refactor parsing and storage of SkGammas (patchset #8 id:280001 of https://codereview.chromium.org/2117773002/ )

Reason for revert:
Tests failing

Original issue's description:
> Refactor parsing and storage of SkGammas
>
> Benefits:
> (1) Parses and stores gamma tags in a single allocation.
> (2) Recognizes equal gamma tags to skip parsing work and
>     save memory.
>
> Non-Benefits:
> (1) Not less complicated.
>
> BUG=skia:
> GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2117773002
>
> Committed: https://skia.googlesource.com/skia/+/2ea944c2b710caf29d4795ac953bad14224796f7
> Committed: https://skia.googlesource.com/skia/+/959ccc1f3f49e1ddeb51c32c30ac4a2d94653856

TBR=reed@google.com,brianosman@google.com,mtklein@google.com
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Review-Url: https://codereview.chromium.org/2171623002