Add comment to make test better understandable (#1850)

Author: Cito

src/utilities/__tests__/buildASTSchema-test.js

@@ -116,6 +116,7 @@ describe('Schema Builder', () => {
       }
     `);
 
+    // String and Boolean are always included through introspection types
     expect(schema.getType('Int')).to.equal(undefined);
     expect(schema.getType('Float')).to.equal(undefined);
     expect(schema.getType('ID')).to.equal(undefined);

src/utilities/__tests__/extendSchema-test.js

@@ -277,6 +277,7 @@ describe('extendSchema', () => {
       }
     `);
 
+    // String and Boolean are always included through introspection types
     expect(schema.getType('Int')).to.equal(undefined);
     expect(schema.getType('Float')).to.equal(undefined);
     expect(schema.getType('String')).to.equal(GraphQLString);