go/parser: add missing parenthesis in a comment
go/parser: add missing parenthesis in a comment

Change-Id: I30783aa6a13ad8348fa24b27672d542a868f96de
GitHub-Last-Rev: c4584ad9dab9736275c2f2554affb6af214f82dd
GitHub-Pull-Request: golang/go#56526
Reviewed-on: https://go-review.googlesource.com/c/go/+/447217
Auto-Submit: Robert Griesemer <a6752097faebf1f02d80107d77a9be009089afe3@google.com>
Run-TryBot: Robert Griesemer <a6752097faebf1f02d80107d77a9be009089afe3@google.com>
TryBot-Result: Gopher Robot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Robert Griesemer <a6752097faebf1f02d80107d77a9be009089afe3@google.com>
Reviewed-by: Bryan Mills <1c8aad60184261ccede67f5c63a0d2a3bf3c9ff4@google.com>

golang/go,golang/go,golang/go,golang/go,golang/go,golang/go,golang/go,golang/go