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

pkg/polymer/test/property_observe_test.html

Index: pkg/polymer/test/property_observe_test.html
diff --git a/pkg/polymer/test/property_observe_test.html b/pkg/polymer/test/property_observe_test.html
index 0c6bbc89200e41c451c45bd83eb4d6a48b289bb4..c1a4ea6aacb70791766dacc9cce9ac3c9fcec8c2 100644
--- a/pkg/polymer/test/property_observe_test.html
+++ b/pkg/polymer/test/property_observe_test.html
@@ -19,6 +19,7 @@ BSD-style license that can be found in the LICENSE file.
     <polymer-element name="x-test2" extends="x-test">
       <template></template>
     </polymer-element>
-    <script type="application/dart" src="property_observe_test.dart"></script>
+    <script type="application/dart;component=1"
+            src="property_observe_test.dart"></script>
   </body>
 </html>