chore(analytics): Include all of angular2 in hello_world

Import dependencies from `angular2/angular2.dart` in `hello_world` to
ensure that any size regressions are caught by our checks.

Update to avoid regressions like #5419.

Closes #5394

modules_dart/payload/hello_world/web/index.dart

@@ -1,55 +1,25 @@
 library hello_world.index;
 
 import "package:angular2/bootstrap.dart" show bootstrap;
-import "package:angular2/core.dart"
-    show ElementRef, Component, Directive, Injectable;
-import "package:angular2/render.dart" show Renderer;
+import "package:angular2/angular2.dart"
+    show Component, Directive, ElementRef, Injectable, Renderer;
 
 main() {
-  // Bootstrapping only requires specifying a root component.
-
-  // The boundary between the Angular application and the rest of the page is
-
-  // the shadowDom of this root component.
-
-  // The selector of the component passed in is used to find where to insert the
-
-  // application.
-
-  // You can use the light dom of the <hello-app> tag as temporary content (for
-
-  // example 'Loading...') before the application is ready.
   bootstrap(HelloCmp);
 }
 
-// A service available to the Injector, used by the HelloCmp component.
 @Injectable()
 class GreetingService {
   String greeting = "hello";
 }
-// Directives are light-weight. They don't allow new
 
-// expression contexts (use @Component for those needs).
 @Directive(selector: "[red]")
 class RedDec {
-  // ElementRef is always injectable and it wraps the element on which the
-
-  // directive was found by the compiler.
   RedDec(ElementRef el, Renderer renderer) {
     renderer.setElementStyle(el, "color", "red");
   }
 }
-// Angular 2.0 supports 2 basic types of directives:
 
-// - Component - the basic building blocks of Angular 2.0 apps. Backed by
-
-//   ShadowDom.(http://www.html5rocks.com/en/tutorials/webcomponents/shadowdom/)
-
-// - Directive - add behavior to existing elements.
-
-// @Component is AtScript syntax to annotate the HelloCmp class as an Angular
-
-// 2.0 component.
 @Component(
     selector: "hello-app",
     viewProviders: const [GreetingService],