Revert "Initial land of SkSL DSL."

This reverts commit 6e599511d44a0d1416df8cc7f76064c97f540e86.

Reason for revert: Breaking bots: https://logs.chromium.org/logs/skia/5061fbd134144011/+/steps/dm/0/stdout

Original change's description:
> Initial land of SkSL DSL.
>
> This is not 100% complete: it lacks support for several kinds of nodes
> and supports only a bare handful of builtin functions, but it
> demonstrates the core functionality and it should be relatively
> straightforward to fill in the missing pieces.
>
> Change-Id: I3058089338e20eebc3da18ac5571801abcaab564
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/331177
> Reviewed-by: John Stiles <johnstiles@google.com>
> Reviewed-by: Brian Osman <brianosman@google.com>
> Commit-Queue: Ethan Nicholas <ethannicholas@google.com>

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

Change-Id: Iee77e5322a0b1efb0f3718ec1f5976a4d4e7323a
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/342620
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
34 files changed