Rename EventEmitter2 to EventEmitter

Fixes #2029

src/browser/TestUtils.test.ts

@@ -3,12 +3,12 @@
  * @license MIT
  */
 
-import { IEvent, EventEmitter2 } from 'common/EventEmitter2';
+import { IEvent, EventEmitter } from 'common/EventEmitter';
 import { ICharSizeService } from 'browser/services/Services';
 
 export class MockCharSizeService implements ICharSizeService {
   get hasValidSize(): boolean { return this.width > 0 && this.height > 0; }
-  onCharSizeChange: IEvent<void> = new EventEmitter2<void>().event;
+  onCharSizeChange: IEvent<void> = new EventEmitter<void>().event;
   constructor(public width: number, public height: number) {}
   measure(): void {}
 }