Fix subscription handling in stream decoder

sdk/lib/async/stream.dart

Index: sdk/lib/async/stream.dart
diff --git a/sdk/lib/async/stream.dart b/sdk/lib/async/stream.dart
index dddc00406cc5ba3a970226010fdd988f5cd4df4f..d5b0335ca5c607a1124e19f4df3f649923068fcf 100644
--- a/sdk/lib/async/stream.dart
+++ b/sdk/lib/async/stream.dart
@@ -1,4 +1,4 @@
-// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
@@ -1014,6 +1014,7 @@ class EventTransformStream<S, T> extends Stream<T> {
                                { void onError(AsyncError error),
                                  void onDone(),
                                  bool unsubscribeOnError }) {
+    unsubscribeOnError = identical(true, unsubscribeOnError);
     return new _EventTransformStreamSubscription(_source, _transformer,
                                                  onData, onError, onDone,
                                                  unsubscribeOnError);