Fix two-way binding in polymer expressions.

pkg/polymer_expressions/test/bindings_test.dart

Index: pkg/polymer_expressions/test/bindings_test.dart
diff --git a/pkg/polymer_expressions/test/bindings_test.dart b/pkg/polymer_expressions/test/bindings_test.dart
index 957b3582873fefcd9ef9a9bc24a2552a67867cbe..c8d1194664c47f74d77ae06f539d996c46f7f817 100644
--- a/pkg/polymer_expressions/test/bindings_test.dart
+++ b/pkg/polymer_expressions/test/bindings_test.dart
@@ -82,8 +82,9 @@ main() => dirtyCheckZone().run(() {
           '<template><input id="i1" value={{x}}></template>'));
       testDiv.append(template.createInstance(model, new PolymerExpressions()));
 
+      var el;
       return new Future(() {
-        var el = testDiv.query("#i1");
+        el = testDiv.query("#i1");
         var subscription = el.onInput.listen(expectAsync((_) {}, count: 1));
         el.focus();
 
@@ -113,8 +114,10 @@ main() => dirtyCheckZone().run(() {
         // selection will be preserved.
         expect(el.selectionStart, 4);
         expect(el.selectionEnd, 4);
-
         subscription.cancel();
+      }).then(_nextMicrotask).then((_) {

[Jennifer Messerly, 2014/05/07 19:30:46]

fyi -- I wonder if we should use requestAnimationFrame too? that way we know it
is still valid even further in the future--right before a render

[Siggi Cherem (dart-lang), 2014/05/07 19:58:15]

Good idea. PTAL

+        expect(el.selectionStart, 4);
+        expect(el.selectionEnd, 4);
       });
     });