chore(docs): rename @private to @internal

The latter is understood by TypeScript's --stripInternal option, so this lets us
rely more on the tooling provided by typescript team.

modules/angular2/src/web_workers/shared/client_message_broker.ts

@@ -17,7 +17,7 @@ export {Type} from "angular2/src/core/facade/lang";
 @Injectable()
 export class ClientMessageBrokerFactory {
   /**
-   * @private
+   * @internal
    */
   constructor(private _messageBus: MessageBus, public _serializer: Serializer) {}
 
@@ -35,7 +35,7 @@ export class ClientMessageBroker {
   private _sink: EventEmitter;
 
   /**
-   * @private
+   * @internal
    */
   constructor(messageBus: MessageBus, public _serializer: Serializer, public channel) {
     this._sink = messageBus.to(channel);

modules/angular2/src/web_workers/shared/service_message_broker.ts

@@ -13,7 +13,7 @@ import {
 @Injectable()
 export class ServiceMessageBrokerFactory {
   /**
-   * @private
+   * @internal
    */
   constructor(private _messageBus: MessageBus, public _serializer: Serializer) {}
 
@@ -37,7 +37,7 @@ export class ServiceMessageBroker {
   private _methods: Map<string, Function> = new Map<string, Function>();
 
   /**
-   * @private
+   * @internal
    */
   constructor(messageBus: MessageBus, private _serializer: Serializer, public channel) {
     this._sink = messageBus.to(channel);