Revert "Update the SkSL pool interface to take an allocation size."

This reverts commit 22ef2257c8624e2383876c6fbb641162fe520228.

Reason for revert: mysterious tree breakage

Original change's description:
> Update the SkSL pool interface to take an allocation size.
>
> Since our end goal no longer has all IRNodes ending up as the exact same
> size in memory, it makes sense for the allocator function to take in a
> desired size. This also opens the door to separate "small" and "large"
> pools, if we want to add pooling support for large but semi-common
> things like Variables.
>
> Change-Id: If3dbe31588adeedede327c5967c344a19507b6fa
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/329961
> Reviewed-by: Brian Osman <brianosman@google.com>
> Commit-Queue: Brian Osman <brianosman@google.com>
> Auto-Submit: John Stiles <johnstiles@google.com>

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

Change-Id: I346948aeb407dc6e6e84835f68d0353e4869ddf7
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/329965
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
3 files changed