refactor(core): support non reflective bootstrap.

This changes Angular so that it can be used without reflection (assuming a codegen for injectors).

BREAKIKNG CHANGE:
- Drops `APP_COMPONENT` provider. Instead, inject
  `ApplicationRef` and read its `componentTypes` property.
- long form bootstrap has changed into the following:
  ```
  var platform = createPlatform(ReflectiveInjector.resolveAndCreate(BROWSER_PROVIDERS));
  var appInjector =
    ReflectiveInjector.resolveAndCreate([BROWSER_APP_PROVIDERS, appProviders], platform.injector);
  coreLoadAndBootstrap(appInjector, MyApp);
  ```

modules/playground/src/web_workers/todo/index.ts

@@ -1,9 +1,4 @@
-import {platform, Provider} from 'angular2/core';
-import {
-  WORKER_RENDER_APPLICATION,
-  WORKER_RENDER_PLATFORM,
-  WORKER_SCRIPT
-} from 'angular2/platform/worker_render';
+import {Provider} from 'angular2/core';
+import {bootstrapRender} from 'angular2/platform/worker_render';
 
-platform([WORKER_RENDER_PLATFORM])
-    .application([WORKER_RENDER_APPLICATION, new Provider(WORKER_SCRIPT, {useValue: "loader.js"})]);
+bootstrapRender("loader.js");