go/types: add test cases for generic constraints, types and functions
Dups: #60856
For #60817
Change-Id: Ic0710758e170d6ceed66649fec08ef8054be4d6b
GitHub-Last-Rev:
8bbc76aaa704f102f9eabdfead45da452e1ea6e6
GitHub-Pull-Request: golang/go#61664
Reviewed-on: https://go-review.googlesource.com/c/go/+/514255
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@google.com>
Run-TryBot: Robert Griesemer <gri@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>