fixes to polymer, gets tests back to a stable state

pkg/observe/test/transform_test.dart

Index: pkg/observe/test/transform_test.dart
diff --git a/pkg/observe/test/transform_test.dart b/pkg/observe/test/transform_test.dart
index 73720cc3f257aa8f8e55b6f91b53fe1f806823f8..064ac87bb5765df245342a46a766c2195ea14e1b 100644
--- a/pkg/observe/test/transform_test.dart
+++ b/pkg/observe/test/transform_test.dart
@@ -36,6 +36,26 @@ main() {
         'extends Base with Mixin, ChangeNotifier implements I1, I2');
   });
 
+  group('adds "with ChangeNotifier" given', () {
+    _testClause('', 'extends ChangeNotifier');
+    _testClause('extends Base', 'extends Base with ChangeNotifier');
+    _testClause('extends Base<T>', 'extends Base<T> with ChangeNotifier');
+    _testClause('extends Base with Mixin',
+        'extends Base with Mixin, ChangeNotifier');
+    _testClause('extends Base with Mixin<T>',
+        'extends Base with Mixin<T>, ChangeNotifier');
+    _testClause('extends Base with Mixin, Mixin2',
+        'extends Base with Mixin, Mixin2, ChangeNotifier');
+    _testClause('implements Interface',
+        'extends ChangeNotifier implements Interface');
+    _testClause('implements Interface<T>',
+        'extends ChangeNotifier implements Interface<T>');
+    _testClause('extends Base implements Interface',
+        'extends Base with ChangeNotifier implements Interface');
+    _testClause('extends Base with Mixin implements I1, I2',
+        'extends Base with Mixin, ChangeNotifier implements I1, I2');
+  });
+
   group('fixes contructor calls ', () {
     _testInitializers('this.a', '(a) : __\$a = a');
     _testInitializers('{this.a}', '({a}) : __\$a = a');