Revert "Merge pull request #4166 from Tyriar/event_with_emitter"

This reverts commit d22f7c9edd, reversing
changes made to 1f8e6f0952.

src/common/public/BufferNamespaceApi.ts

@@ -5,19 +5,20 @@
 
 import { IBuffer as IBufferApi, IBufferNamespace as IBufferNamespaceApi } from 'xterm';
 import { BufferApiView } from 'common/public/BufferApiView';
-import { IEvent, EventEmitter, initEvent } from 'common/EventEmitter';
+import { IEvent, EventEmitter } from 'common/EventEmitter';
 import { ICoreTerminal } from 'common/Types';
 
 export class BufferNamespaceApi implements IBufferNamespaceApi {
   private _normal: BufferApiView;
   private _alternate: BufferApiView;
 
-  public readonly onBufferChange = initEvent<IBufferApi>();
+  private readonly _onBufferChange = new EventEmitter<IBufferApi>();
+  public readonly onBufferChange = this._onBufferChange.event;
 
   constructor(private _core: ICoreTerminal) {
     this._normal = new BufferApiView(this._core.buffers.normal, 'normal');
     this._alternate = new BufferApiView(this._core.buffers.alt, 'alternate');
-    this._core.buffers.onBufferActivate(() => this.onBufferChange.fire(this.active));
+    this._core.buffers.onBufferActivate(() => this._onBufferChange.fire(this.active));
   }
   public get active(): IBufferApi {
     if (this._core.buffers.active === this._core.buffers.normal) { return this.normal; }