message: docs(observable): add a description for toPromise
  fix
diff: @@ -251,9 +251,9 @@ export class Observable<T> implements Subscribable<T> {
  /**
  * @method forEach
  - * @param {Function} next a handler for each value emitted by the observable
  - * @param {PromiseConstructor} [promiseCtor] a constructor function used to instantiate the Promise
  - * @return {Promise} a promise that either resolves on observable completion or
  + * @param next a handler for each value emitted by the observable
  + * @param [promiseCtor] a constructor function used to instantiate the Promise
  + * @return a promise that either resolves on observable completion or
  * rejects with the handled error
  */
  forEach(next: (value: T) => void, promiseCtor?: PromiseConstructorLike): Promise<void> {
  @@ -352,6 +352,16 @@ export class Observable<T> implements Subscribable<T> {
  toPromise<T>(this: Observable<T>, PromiseCtor: PromiseConstructorLike): Promise<T>;
  /* tslint:enable:max-line-length */
  + /**
  + * Subscribe to this Observable and get a Promise resolving on
  + * `complete` with the last emission.
  + *
  + * @method toPromise
  + * @param [promiseCtor] a constructor function used to instantiate
  + * the Promise
  + * @return A Promise that resolves with the last value emit, or
  + * rejects on an error.
  + */
  toPromise(promiseCtor?: PromiseConstructorLike): Promise<T> {
  promiseCtor = getPromiseCtor(promiseCtor);
  