Improves how to initialize polymer apps and fixes polymer build and linter to

samples/third_party/todomvc/test/markdone_shadow_test.dart

Index: samples/third_party/todomvc/test/markdone_shadow_test.dart
diff --git a/samples/third_party/todomvc/test/markdone_shadow_test.dart b/samples/third_party/todomvc/test/markdone_shadow_test.dart
index 5e5dc9ad444226fbfc91125a52ef33bafadf0772..0acc50828f36a3d96480f8432f7df85c9b203968 100644
--- a/samples/third_party/todomvc/test/markdone_shadow_test.dart
+++ b/samples/third_party/todomvc/test/markdone_shadow_test.dart
@@ -7,11 +7,10 @@ library todomvc.test.markdone_shadow_test;
 // We don't use this import, but it signals to the test framework that this is
 // a web test.
 import 'dart:html';
-import 'package:polymer/polymer.dart' show initMethod;
 import 'markdone_test.dart' as markdone_test;
 
-@initMethod _main() {
+main() {
   // Make analyzer happy by using dart:html.
   document.query('body');
-  markdone_test.init();
+  markdone_test.main();
 }