Remove AsyncError with Expando.

tests/lib/async/stream_subscription_as_future_test.dart

Index: tests/lib/async/stream_subscription_as_future_test.dart
diff --git a/tests/lib/async/stream_subscription_as_future_test.dart b/tests/lib/async/stream_subscription_as_future_test.dart
index 8fe2ca6ce4ef29329b81e2aa7f097efd580447cc..5be8f7951bec3e20b2d7aad41df63b648df8433c 100644
--- a/tests/lib/async/stream_subscription_as_future_test.dart
+++ b/tests/lib/async/stream_subscription_as_future_test.dart
@@ -48,8 +48,8 @@ main() {
     Stream stream = controller.stream;
     var output = [];
     var subscription = stream.listen((x) { output.add(x); });
-    subscription.asFuture(output).catchError(expectAsync1((e) {
-      Expect.equals(e.error, "foo");
+    subscription.asFuture(output).catchError(expectAsync1((error) {
+      Expect.equals(error, "foo");
     }));
   });
 
@@ -61,8 +61,8 @@ main() {
       });
     var output = [];
     var subscription = stream.listen((x) { output.add(x); });
-    subscription.asFuture(output).catchError(expectAsync1((e) {
-      Expect.equals(e.error, "foo");
+    subscription.asFuture(output).catchError(expectAsync1((error) {
+      Expect.equals(error, "foo");
     }));
   });
 }