Correct a code comment
Correct a code comment

Description got stale over the evolution of the PR:

https://github.com/graphql/graphql-js/pull/701

jjergus/graphql-js,gabelevi/graphql-js,enaqx/graphql-js,gabelevi/graphql-js,tgriesser/graphql-js,graphql/graphql-js,tgriesser/graphql-js,enaqx/graphql-js,baer/graphql-js,enaqx/graphql-js,baer/graphql-js,graphql/graphql-js,jjergus/graphql-js,graphql/graphql-js