refactor: remove EventEmitter from facade (#14837)

As of right now each module has its own copy of the EventEmitter
contributing to bloat.

modules/@angular/forms/test/form_group_spec.ts

@@ -6,11 +6,11 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
+import {EventEmitter} from '@angular/core';
 import {async, fakeAsync, tick} from '@angular/core/testing';
 import {AsyncTestCompleter, beforeEach, describe, inject, it} from '@angular/core/testing/testing_internal';
 import {AbstractControl, FormArray, FormControl, FormGroup, Validators} from '@angular/forms';
 
-import {EventEmitter} from '../src/facade/async';
 import {isPresent} from '../src/facade/lang';
 
 export function main() {