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

pkg/polymer/test/event_path_declarative_test.dart

Index: pkg/polymer/test/event_path_declarative_test.dart
diff --git a/pkg/polymer/test/event_path_declarative_test.dart b/pkg/polymer/test/event_path_declarative_test.dart
index 9983d13a5eacf0268cf8cd6560b8350767b406d2..1d8c2d154e36a15bf9e4128be41128ba46bde336 100644
--- a/pkg/polymer/test/event_path_declarative_test.dart
+++ b/pkg/polymer/test/event_path_declarative_test.dart
@@ -18,8 +18,6 @@ import 'package:polymer/polymer.dart';
 var _observedEvents = [];
 var _testFired;
 
-main() => initPolymer();
-
 @reflectable
 class XZug extends PolymerElement {
 
@@ -79,7 +77,7 @@ class XBar extends PolymerElement {
   }
 }
 
-@initMethod init() {
+@initMethod main() {
   useHtmlConfiguration();
   // TODO(sigmund): switch back to use @CustomTag. We seem to be running into a
   // problem where using @CustomTag doesn't guarantee that we register the tags