feat(WebWorker): Expose MessageBroker API

Closes #3942

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

@@ -12,6 +12,7 @@ import {ListWrapper, StringMapWrapper, MapWrapper} from "angular2/src/core/facad
 import {Serializer} from "angular2/src/web_workers/shared/serializer";
 import {Injectable} from "angular2/di";
 import {Type, StringWrapper} from "angular2/src/core/facade/lang";
+export {Type} from "angular2/src/core/facade/lang";
 
 @Injectable()
 export class ClientMessageBrokerFactory {
@@ -29,7 +30,8 @@ export class ClientMessageBroker {
   constructor(messageBus: MessageBus, protected _serializer: Serializer, public channel) {
     this._sink = messageBus.to(channel);
     var source = messageBus.from(channel);
-    ObservableWrapper.subscribe(source, (message) => this._handleMessage(message));
+    ObservableWrapper.subscribe(source,
+                                (message: StringMap<string, any>) => this._handleMessage(message));
   }
 
   private _generateMessageId(name: string): string {
@@ -43,7 +45,7 @@ export class ClientMessageBroker {
     return id;
   }
 
-  runOnUiThread(args: UiArguments, returnType: Type): Promise<any> {
+  runOnService(args: UiArguments, returnType: Type): Promise<any> {
     var fnArgs = [];
     if (isPresent(args.args)) {
       ListWrapper.forEach(args.args, (argument) => {
@@ -128,7 +130,7 @@ class MessageData {
 }
 
 export class FnArg {
-  constructor(public value, public type) {}
+  constructor(public value, public type: Type) {}
 }
 
 export class UiArguments {