SkSL: Turn DSL parser off again

Several fuzzer issues, and one Chromium issue that's blocking the roll.

Bug: chromium:1246795
Bug: skia:12423
Change-Id: I00370b74569b447e543d9a1f22c588eb493063da
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/445960
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: Brian Osman <brianosman@google.com>
44 files changed