fix(exception_handler): fix error messages of wrapped exceptions

Closes #4117

modules/angular2/src/web_workers/shared/generic_message_bus.dart

@@ -6,6 +6,7 @@ import 'package:angular2/src/web_workers/shared/message_bus.dart'
     show MessageBus, MessageBusSink, MessageBusSource;
 import 'package:angular2/src/core/zone/ng_zone.dart';
 import 'package:angular2/src/core/facade/lang.dart';
+import 'package:angular2/src/core/facade/exceptions.dart';
 
 class GenericMessageBus implements MessageBus {
   final MessageBusSink _sink;

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

@@ -1,5 +1,5 @@
 import {EventEmitter} from 'angular2/src/core/facade/async';
-import {BaseException} from 'angular2/src/core/facade/lang';
+import {BaseException, WrappedException} from 'angular2/src/core/facade/exceptions';
 import {NgZone} from 'angular2/src/core/zone/ng_zone';
 export {EventEmitter, Observable} from 'angular2/src/core/facade/async';
 

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

@@ -3,7 +3,7 @@ import {
   MessageBusSource,
   MessageBusSink
 } from "angular2/src/web_workers/shared/message_bus";
-import {BaseException} from 'angular2/src/core/facade/lang';
+import {BaseException, WrappedException} from 'angular2/src/core/facade/exceptions';
 import {EventEmitter} from 'angular2/src/core/facade/async';
 import {StringMap, StringMapWrapper} from 'angular2/src/core/facade/collection';
 import {Injectable} from "angular2/src/core/di";

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

@@ -3,9 +3,10 @@ import {
   isArray,
   isPresent,
   serializeEnum,
-  deserializeEnum,
-  BaseException
+  deserializeEnum
 } from "angular2/src/core/facade/lang";
+import {BaseException, WrappedException} from 'angular2/src/core/facade/exceptions';
+
 import {
   ListWrapper,
   Map,