This is a reland of b292c30aa0
This CL also addresses the Wuffs-specific unreachable code.
Original change's description:
> Reenable unreachable-code warnings.
>
> Change-Id: Ie56967a4b823388f0975384e88be23ff2fceecf7
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/504598
> Reviewed-by: Brian Osman <brianosman@google.com>
> Commit-Queue: John Stiles <johnstiles@google.com>
> Auto-Submit: John Stiles <johnstiles@google.com>
Change-Id: I655db50134e0de0d0448f22b636ba027513e28f4
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/504757
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
b73789dc4a