Adapt streams for additional stackTrace argument.

R=lrn@google.com

Review URL: https://codereview.chromium.org//25094002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart/pkg/mime@28511 260f80e4-7a28-3924-810f-c04153c831b5
diff --git a/lib/src/mime_multipart_transformer.dart b/lib/src/mime_multipart_transformer.dart
index 5813087..024cd71 100644
--- a/lib/src/mime_multipart_transformer.dart
+++ b/lib/src/mime_multipart_transformer.dart
@@ -21,7 +21,7 @@
 
   StreamSubscription<List<int>> listen(void onData(List<int> data),
                                        {void onDone(),
-                                        void onError(error),
+                                        Function onError,
                                         bool cancelOnError}) {
     return _stream.listen(onData,
                           onDone: onDone,
@@ -138,9 +138,7 @@
                 }
                 _controller.close();
               },
-              onError: (error) {
-                _controller.addError(error);
-              });
+              onError: _controller.addError);
         });
     return _controller.stream;
   }