This is a rewrite to drop the type keyword for parameterized functions
and types, and to instead always provide a constraint.
We can revert if we don't like this approach.
Change-Id: If4669fb4e2015067e9f955ff8567ed421be639ea
Reviewed-on: https://go-review.googlesource.com/c/go/+/248880
Reviewed-by: Ian Lance Taylor <iant@golang.org>
We can roll back this CL if we go back to parentheses.
Change-Id: Ideb7dbe8e3c4499d76518a5c9b6f7931a7c103a4
Reviewed-on: https://go-review.googlesource.com/c/go/+/243158
Reviewed-by: Ian Lance Taylor <iant@golang.org>