Reland "Eliminate the SkSL SharedCompiler."

This reverts commit 8a404fea2cac8b5d97430114baaa77e6bee3c567.

Reason for revert: fixed ASAN at http://review.skia.org/573957

Original change's description:
> Revert "Eliminate the SkSL SharedCompiler."
>
> This reverts commit 6d4f3bcfb4c81226b2a62ebe0e8ec33e5608d958.
>
> Reason for revert: possible TAP breakage
>
> https://fusion2.corp.google.com/ci/tap/image_tenor/activity/470054018/invocations/be052aee-3deb-4d74-a891-728f6252bd78/targets/%2F%2Fimage%2Ftenor%2Feleven%2Ftools:dynamic_content_author_handler_test/history;cl=470054018/be052aee-3deb-4d74-a891-728f6252bd78/tests
>
> Original change's description:
> > Eliminate the SkSL SharedCompiler.
> >
> > Compiler creation is now fast and lightweight. Keeping a shared
> > compiler instance around no longer adds value.
> >
> > Change-Id: I49f6cd4c2c69774093c5deb617a406420fb91595
> > Bug: skia:13666
> > Reviewed-on: https://skia-review.googlesource.com/c/skia/+/573263
> > Reviewed-by: Brian Osman <brianosman@google.com>
> > Commit-Queue: John Stiles <johnstiles@google.com>
> > Auto-Submit: John Stiles <johnstiles@google.com>
>
> Bug: skia:13666
> Change-Id: I8c1a6f028348425493865447bbfdb75bd4792319
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/573856
> Auto-Submit: John Stiles <johnstiles@google.com>
> Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
> Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>

Bug: skia:13666
Change-Id: I5fb22f2faecd3bbf5b19c636b766b23b316e7d04
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/573958
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: John Stiles <johnstiles@google.com>
7 files changed