Changes in polymer-expressions to prepare for codegen in polymer:

pkg/polymer_expressions/test/eval_test.dart

Index: pkg/polymer_expressions/test/eval_test.dart
diff --git a/pkg/polymer_expressions/test/eval_test.dart b/pkg/polymer_expressions/test/eval_test.dart
index 1f4bee650fc1295e61d57a1d23bbbb4a1accee7e..2181215eb887734966d55aa0c17e4ef764e5d916 100644
--- a/pkg/polymer_expressions/test/eval_test.dart
+++ b/pkg/polymer_expressions/test/eval_test.dart
@@ -295,7 +295,7 @@ main() {
 
     test("should a field from the parent's model", () {
       var parent = new Scope(variables: {'a': 'A', 'b': 'B'});
-      var child = new Scope(variables: {'a': 'a'}, parent: parent);
+      var child = parent.childScope('a', 'a');
       expect(child['a'], 'a');
       expect(parent['a'], 'A');
       expect(child['b'], 'B');