Ember - Add additional type defs for RSVP namespace (#16359)

* add additional type defs for RSVP

* satisfy linting

types/ember/index.d.ts

@@ -1,6 +1,7 @@
 // Type definitions for Ember.js 2.7
 // Project: http://emberjs.com/
 // Definitions by: Jed Mao <https://github.com/jedmao>
+//                 bttf <https://github.com/bttf>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 
 /// <reference types="jquery" />
@@ -1571,6 +1572,34 @@ declare namespace Ember {
             @return {Promise}
             */
             finally<V>(callback: (a: T) => V, label?: string): Promise<V, U>;
+
+            static all<Q, R>(promises: GlobalArray<(Q | Thenable<Q, R>)>): Promise<Q[], R>;
+            static race<Q, R>(promises: GlobalArray<Promise<Q, R>>): Promise<Q, R>;
+
+            /**
+             @method resolve
+             @param {Any} value value that the returned promise will be resolved with
+             @param {String} label optional string for identifying the returned promise.
+             Useful for tooling.
+             @return {Promise} a promise that will become fulfilled with the given
+             `value`
+             */
+            static resolve<Q, R>(object?: Q | Thenable<Q, R>): Promise<Q, R>;
+
+            /**
+             @method cast (Deprecated in favor of resolve
+             @param {Any} value value that the returned promise will be resolved with
+             @param {String} label optional string for identifying the returned promise.
+             Useful for tooling.
+             @return {Promise} a promise that will become fulfilled with the given
+             `value`
+             */
+            static cast<Q, R>(object: Q | Thenable<Q, R>, label?: string): Promise<Q, R>;
+
+            /**
+             `RSVP.Promise.reject` returns a promise rejected with the passed `reason`.
+             */
+            static reject(reason?: any): Promise<any, any>;
         }
 
         function all(promises: GlobalArray<Promise<any, any>>): Promise<any, any>;