Removed polymer & mirror from Observatory

runtime/observatory/web/main.dart

Index: runtime/observatory/web/main.dart
diff --git a/runtime/observatory/web/main.dart b/runtime/observatory/web/main.dart
index 36c03ab1165391d55ef8b4c35ad74444bf05ff01..ae05afe5c0fbbda33c80cb729fe10e2dcd8915bf 100644
--- a/runtime/observatory/web/main.dart
+++ b/runtime/observatory/web/main.dart
@@ -4,7 +4,6 @@
 
 import 'dart:html';
 import 'package:logging/logging.dart';
-import 'package:polymer/polymer.dart';
 import 'package:observatory/elements.dart';
 
 main() async {
@@ -21,10 +20,6 @@ main() async {
   });
   await initElements();
   Logger.root.info('Starting Observatory');
-  await initPolymer();
-  Logger.root.info('Polymer initialized');
-  await Polymer.onReady;
-  Logger.root.info('Polymer elements have been upgraded');
   document.body.children
       .insert(0, document.createElement('observatory-application'));
 }