cmd/compile/internal/types2: use type variables consistently in Checker.conversion
We have V and T and Vu and Tu. When calling the various isX predicates
consistently use Vu and Tu.
(We could also use V an T because the predicates call under anyway,
but using Vu and Tu removes an unnecessary call to Named.under if
V or T are *Named.)
Also, removed some outdated comments.
Change-Id: I6fcd9ce5f6292e89ac2afd597b72fd0790e84ff1
Reviewed-on: https://go-review.googlesource.com/c/go/+/362895
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Robert Findley <rfindley@google.com>