test/typeparam: add a test case for issue46591
test/typeparam: add a test case for issue46591

Fixes #46591

Change-Id: I4875092ecd7760b0cd487e793576ef7a9a569a0e
Reviewed-on: https://go-review.googlesource.com/c/go/+/343970
Reviewed-by: Matthew Dempsky <e56ac2c500064424afac424d4b5e53bd0570a731@google.com>
Reviewed-by: Robert Griesemer <a6752097faebf1f02d80107d77a9be009089afe3@golang.org>
Trust: Matthew Dempsky <e56ac2c500064424afac424d4b5e53bd0570a731@google.com>
Run-TryBot: Matthew Dempsky <e56ac2c500064424afac424d4b5e53bd0570a731@google.com>
Run-TryBot: Robert Griesemer <a6752097faebf1f02d80107d77a9be009089afe3@golang.org>
TryBot-Result: Go Bot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>

golang/go,nawawi/go,cloudflare/go,cloudflare/go,nawawi/go,CAFxX/go,nawawi/go,cloudflare/go,CAFxX/go,cloudflare/go,cloudflare/go,CAFxX/go,nawawi/go,cloudflare/go,nawawi/go,golang/go,golang/go,cloudflare/go,CAFxX/go,nawawi/go,golang/go,nawawi/go,CAFxX/go,golang/go,cloudflare/go,golang/go,golang/go,golang/go,CAFxX/go,CAFxX/go,CAFxX/go,nawawi/go