Revert "switched SkSL interpreter over to threaded code"

This reverts commit adecf4b6d5fe034cd98c691d340483d1d6cc3b77.

Reason for revert: breaking the entire world

Original change's description:
> switched SkSL interpreter over to threaded code
> 
> Bug: skia:
> Change-Id: I2a7b772a874aa920b8509214c25e874020c896ce
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/238962
> Reviewed-by: Brian Osman <brianosman@google.com>
> Commit-Queue: Ethan Nicholas <ethannicholas@google.com>

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

Change-Id: I1d5ce9d11b2d94feb29c9bd2f0608526ddea2d99
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/239556
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
4 files changed