fix(WebWorker): Fix Todo Server demo and add test to ensure the demo can bootstrap.

Closes #3970

modules/examples/pubspec.yaml

@@ -35,6 +35,15 @@ transformers:
         - web/src/observable_models/index.dart
         - web/src/person_management/index.dart
         - web/src/template_driven_forms/index.dart
+        - web/src/web_workers/todo/server_index.dart
+        - web/src/web_workers/todo/background_index.dart
+        - web/src/web_workers/message_broker/background_index.dart
+        - web/src/web_workers/kitchen_sink/background_index.dart
+
+        # These entrypoints are disabled untl the transformer supports UI bootstrap (issue #3971)
+        # - web/src/web_workers/message_broker/index.dart
+        # - web/src/web_workers/kitchen_sink/index.dart
+        # - web/src/web_workers/todo/index.dart
         # These entrypoints are disabled until cross-package urls are working (issue #2982)
         # - web/src/material/button/index.dart
         # - web/src/material/checkbox/index.dart

modules/examples/src/web_workers/todo/index_common.ts

@@ -1,6 +1,4 @@
-import {NgFor} from 'angular2/src/core/directives/ng_for';
-import {View, Component} from 'angular2/src/core/metadata';
-import {FORM_DIRECTIVES} from 'angular2/src/forms/directives';
+import {NgFor, View, Component, FORM_DIRECTIVES} from 'angular2/web_worker/worker';
 import {Store, Todo, TodoFactory} from './services/TodoStore';
 
 @Component({selector: 'todo-app', viewBindings: [Store, TodoFactory]})

modules/examples/src/web_workers/todo/services/TodoStore.ts

@@ -1,4 +1,4 @@
-import {Injectable} from 'angular2/angular2';
+import {Injectable} from 'angular2/web_worker/worker';
 import {ListWrapper, Predicate} from 'angular2/src/core/facade/collection';
 
 // base model for RecordStore