This is a port of CL 306169 to go/types, adjusted only for use of the
typeparams package, and the different positioning API.
Change-Id: I3095f4b0dae4473e75ec2a988ea282bac1a4bab3
Reviewed-on: https://go-review.googlesource.com/c/go/+/312189
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Robert Griesemer <gri@golang.org>