refactor: remove unnecessary annotations

modules/@angular/core/testing/ng_zone_mock.ts

@@ -6,7 +6,6 @@ import {EventEmitter, ObservableWrapper} from '../src/facade/async';
  */
 @Injectable()
 export class MockNgZone extends NgZone {
-  /** @internal */
   private _mockOnStable: EventEmitter<any> = new EventEmitter(false);
 
   constructor() { super({enableLongStackTrace: false}); }

modules/@angular/core/testing/testing_internal.ts

@@ -212,7 +212,6 @@ export class SpyObject {
     return object;
   }
 
-  /** @internal */
   _createGuinnessCompatibleSpy(name): GuinessCompatibleSpy {
     var newSpy: GuinessCompatibleSpy = <any>jasmine.createSpy(name);
     newSpy.andCallFake = <any>newSpy.and.callFake;

modules/@angular/platform-browser/src/web_workers/shared/client_message_broker.ts

@@ -20,7 +20,7 @@ export abstract class ClientMessageBrokerFactory {
 @Injectable()
 export class ClientMessageBrokerFactory_ extends ClientMessageBrokerFactory {
   /** @internal */
-  public _serializer: Serializer;
+  _serializer: Serializer;
   constructor(private _messageBus: MessageBus, _serializer: Serializer) {
     super();
     this._serializer = _serializer;

modules/@angular/platform-browser/src/web_workers/shared/service_message_broker.ts

@@ -15,7 +15,7 @@ export abstract class ServiceMessageBrokerFactory {
 @Injectable()
 export class ServiceMessageBrokerFactory_ extends ServiceMessageBrokerFactory {
   /** @internal */
-  public _serializer: Serializer;
+  _serializer: Serializer;
 
   constructor(private _messageBus: MessageBus, _serializer: Serializer) {
     super();