go/types, types2: use ":" as start of implicit type switch case scopes
Adjust the respective API test accordingly.
Change-Id: I7ecc8899b40ae3b5aeb2c1e032935c672b41e0b6
Reviewed-on: https://go-review.googlesource.com/c/go/+/592675 Reviewed-by: Robert Findley <rfindley@google.com> Reviewed-by: Robert Griesemer <gri@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>