Remove AsyncError with Expando.

sdk/lib/isolate/isolate_stream.dart

Index: sdk/lib/isolate/isolate_stream.dart
diff --git a/sdk/lib/isolate/isolate_stream.dart b/sdk/lib/isolate/isolate_stream.dart
index cb4ca7711e024d2170206b3bf654c9b4bf0c40d1..0f0f63fc9e530c615c5e1ec1183c88f9de333203 100644
--- a/sdk/lib/isolate/isolate_stream.dart
+++ b/sdk/lib/isolate/isolate_stream.dart
@@ -77,7 +77,7 @@ class IsolateStream extends Stream<dynamic> {
   }
 
   StreamSubscription listen(void onData(event),
-                            { void onError(AsyncError error),
+                            { void onError(error),
                               void onDone(),
                               bool cancelOnError}) {
       return _controller.stream.listen(onData,
@@ -114,7 +114,7 @@ abstract class IsolateSink extends EventSink<dynamic> {
    */
   void add(dynamic message);
 
-  void addError(AsyncError errorEvent);
+  void addError(errorEvent);
 
   /** Closing multiple times is allowed. */
   void close();