This reverts commit 0596094b81.
Reason for revert: Flutter somehow still references skstd::optional
flutter_engine in google3 still has old code:
http://screen/BHDrjqwzchdFVfQ
Original change's description:
> Remove skstd::optional entirely.
>
> Change-Id: Id9862712ea3e769797abd654922879ce6bc4487c
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/504976
> Reviewed-by: Ben Wagner <bungeman@google.com>
> Reviewed-by: Brian Osman <brianosman@google.com>
> Commit-Queue: John Stiles <johnstiles@google.com>
Change-Id: Idea391399c2e11b83d5a130023adb340d40cadcb
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/505396
Auto-Submit: John Stiles <johnstiles@google.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Reviewed-by: Heather Miller <hcm@google.com>
Commit-Queue: Heather Miller <hcm@google.com>
156e7d15a4