graphql-js

f201681b - Fix ambiguity around when schema definition may be omitted (#3839)

Fix ambiguity around when schema definition may be omitted (#3839) This PR implements the tests and fixes necessary for [Spec RFC #987](https://github.com/graphql/graphql-spec/pull/987). This PR is made of three main commits: 1. Test printing a schema that has `Query`, `Mutation` and `Virus` types, but only supports `query` operations (via the `Query` type) and does _not_ support `mutation` operations. 2. Test parsing this same schema text, and assert that the schema does not have a mutation type. 3. Fix the printing of the schema. Co-authored-by: Lee Byron <lee@leebyron.com>