Replace bootstrap logic with 'boot.js', use 'component/dart' mime-type and add

samples/third_party/todomvc/test/mainpage_test.dart

Index: samples/third_party/todomvc/test/mainpage_test.dart
diff --git a/samples/third_party/todomvc/test/mainpage_test.dart b/samples/third_party/todomvc/test/mainpage_test.dart
index e5b94ff507837743a0c9c86f81ce76f38a88c404..4c7f6add4b6400c8e8229086602aab53d8ab2700 100644
--- a/samples/third_party/todomvc/test/mainpage_test.dart
+++ b/samples/third_party/todomvc/test/mainpage_test.dart
@@ -17,8 +17,8 @@ import 'utils.dart';
 /**
  * This test runs the TodoMVC app and checks the state of the initial page.
  */
+@initMethod
 main() {
-  initPolymer();
   useHtmlConfiguration();
 
   setUp(() => Polymer.onReady);