Remove special case in assertValidName (#1232)

This __configs__ special case for assertValidName is no longer necessary now that we have the allowedLegacyNames mechanism.

Author: leebyron

src/utilities/__tests__/assertValidName-test.js

@@ -23,8 +23,4 @@ describe('assertValidName()', () => {
   it('throws for names with invalid characters', () => {
     expect(() => assertValidName('>--()-->')).to.throw(/Names must match/);
   });
-
-  it('does not throw for legacy servers that use __configs__ introspection', () => {
-    expect(() => assertValidName('__configs__')).not.to.throw();
-  });
 });

src/utilities/assertValidName.js

@@ -32,15 +32,7 @@ export function isValidNameError(
   node?: ASTNode | void,
 ): GraphQLError | void {
   invariant(typeof name === 'string', 'Expected string');
-  if (
-    name.length > 1 &&
-    name[0] === '_' &&
-    name[1] === '_' &&
-    // Note: this special case is not part of the spec and exists only to
-    // support legacy server configurations. Do not rely on this special case
-    // as it may be removed at any time.
-    name !== '__configs__'
-  ) {
+  if (name.length > 1 && name[0] === '_' && name[1] === '_') {
     return new GraphQLError(
       `Name "${name}" must not begin with "__", which is reserved by ` +
         'GraphQL introspection.',