Roll polymer packages to version 0.3.4

pkg/observe/lib/src/list_path_observer.dart

Index: pkg/observe/lib/src/list_path_observer.dart
diff --git a/pkg/observe/lib/src/list_path_observer.dart b/pkg/observe/lib/src/list_path_observer.dart
index bab01c230fd5d121ae9ef534fe2fb8d9d27f9a49..22a81995989483ad5876c4e2328c05a4f44e3584 100644
--- a/pkg/observe/lib/src/list_path_observer.dart
+++ b/pkg/observe/lib/src/list_path_observer.dart
@@ -12,6 +12,7 @@ import 'package:observe/observe.dart';
 // The main difference is we support anything on the rich Dart Iterable API.
 
 /// Observes a path starting from each item in the list.
+@deprecated
 class ListPathObserver<E, P> extends ChangeNotifier {
   final ObservableList<E> list;
   final String _itemPath;
@@ -59,7 +60,7 @@ class ListPathObserver<E, P> extends ChangeNotifier {
     if (lengthAdjust > 0) {
       for (int i = 0; i < lengthAdjust; i++) {
         int len = _observers.length;
-        var pathObs = new PathObserver(list, '$len.$_itemPath');
+        var pathObs = new PathObserver(list, '[$len].$_itemPath');
         pathObs.open(_scheduleReduce);
         _observers.add(pathObs);
       }