Revert of Make SkSmallAllocator obey the RAII invariants and be expandable (patchset...

Revert of Make SkSmallAllocator obey the RAII invariants and be expandable (patchset #15 id:280001 of https://codereview.chromium.org/2488523003/ )

Reason for revert:
bots crashing / asserting

Original issue's description:
> Make SkSmallAllocator obey the RAII invariants and move to heap structures when needed.
>
> The biggest change is to the API which allowed code to bypass the
> destruction invariants. This destruction bypass feature was needed in
> only one use, and is totally encapsulated using createWithIniterT.
>
> BUG=skia:
> GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2488523003
>
> Committed: https://skia.googlesource.com/skia/+/d5dc657b8c3ac916f98005dafdedafe02f023449
> Committed: https://skia.googlesource.com/skia/+/c18b5f8f57a4efc5d5d1e399ed8bd3bd02c592ab

TBR=bungeman@google.com,herb@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/2494353002