feat: add type for [Symbol.toStringTag] getter

Author: saihaj

src/type/definition.d.ts

@@ -182,6 +182,7 @@ export class GraphQLList<T extends GraphQLType> {
   toString: () => string;
   toJSON: () => string;
   inspect: () => string;
+  get [Symbol.toStringTag](): string;
 }
 
 /**
@@ -212,6 +213,7 @@ export class GraphQLNonNull<T extends GraphQLNullableType> {
   toString: () => string;
   toJSON: () => string;
   inspect: () => string;
+  get [Symbol.toStringTag](): string;
 }
 
 export type GraphQLWrappingType = GraphQLList<any> | GraphQLNonNull<any>;
@@ -399,6 +401,7 @@ export class GraphQLObjectType<TSource = any, TContext = any> {
   toString(): string;
   toJSON(): string;
   inspect(): string;
+  get [Symbol.toStringTag](): string;
 }
 
 export function argsToArgsConfig(
@@ -551,6 +554,7 @@ export class GraphQLInterfaceType {
   toString(): string;
   toJSON(): string;
   inspect(): string;
+  get [Symbol.toStringTag](): string;
 }
 
 export interface GraphQLInterfaceTypeConfig<TSource, TContext> {
@@ -612,6 +616,7 @@ export class GraphQLUnionType {
   toString(): string;
   toJSON(): string;
   inspect(): string;
+  get [Symbol.toStringTag](): string;
 }
 
 export interface GraphQLUnionTypeConfig<TSource, TContext> {
@@ -675,6 +680,7 @@ export class GraphQLEnumType {
   toString(): string;
   toJSON(): string;
   inspect(): string;
+  get [Symbol.toStringTag](): string;
 }
 
 export interface GraphQLEnumTypeConfig {
@@ -744,6 +750,7 @@ export class GraphQLInputObjectType {
   toString(): string;
   toJSON(): string;
   inspect(): string;
+  get [Symbol.toStringTag](): string;
 }
 
 export interface GraphQLInputObjectTypeConfig {

src/type/directives.d.ts

@@ -39,6 +39,7 @@ export class GraphQLDirective {
   toString(): string;
   toJSON(): string;
   inspect(): string;
+  get [Symbol.toStringTag](): string;
 }
 
 export interface GraphQLDirectiveConfig {

src/type/schema.d.ts

@@ -82,6 +82,7 @@ export class GraphQLSchema {
     extensionASTNodes: ReadonlyArray<SchemaExtensionNode>;
     assumeValid: boolean;
   };
+  get [Symbol.toStringTag](): string;
 }
 
 type TypeMap = ObjMap<GraphQLNamedType>;