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

samples/searchable_list/test/demo_app_test.dart

Index: samples/searchable_list/test/demo_app_test.dart
diff --git a/samples/searchable_list/test/demo_app_test.dart b/samples/searchable_list/test/demo_app_test.dart
index 564cef3f72ac0b6949245ceab4809c95d84a3cd6..13973010e956b7e3425481d1a062ffb3a84bfd05 100644
--- a/samples/searchable_list/test/demo_app_test.dart
+++ b/samples/searchable_list/test/demo_app_test.dart
@@ -15,8 +15,8 @@ import '../web/elements/demo_app.dart';
  * A trivial test to get the analyzer plugged into this sample. See
  * searchable_list_test.dart.
  */
+@initMethod
 main() {
-  initPolymer();
   useHtmlConfiguration();
 
   setUp(() => Polymer.onReady);