spec: adjust rules to use core or specific types as necessary
spec: adjust rules to use core or specific types as necessary

Change-Id: I64280c1bb9608d7781514f237ac70c6abbfde9f6
Reviewed-on: https://go-review.googlesource.com/c/go/+/384754
Trust: Robert Griesemer <a6752097faebf1f02d80107d77a9be009089afe3@golang.org>
Run-TryBot: Robert Griesemer <a6752097faebf1f02d80107d77a9be009089afe3@golang.org>
TryBot-Result: Gopher Robot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>

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