go/types, types2: use slices to simplify the code
Simplify the code and remove some unnecessary helper functions.
Change-Id: I1419ca3a0c7048891bbdc274f53fd72960410651
GitHub-Last-Rev:
06b1f03bb36cf1028a52f0223af81cf74ec4d77c
GitHub-Pull-Request: golang/go#68732
Reviewed-on: https://go-review.googlesource.com/c/go/+/602719
Reviewed-by: Robert Griesemer <gri@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Robert Findley <rfindley@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>