Fix return-type for error-handlers in streams.

sdk/lib/async/stream_impl.dart

Index: sdk/lib/async/stream_impl.dart
diff --git a/sdk/lib/async/stream_impl.dart b/sdk/lib/async/stream_impl.dart
index dffaa1205910b222ea7ca6bbdbf197069f33cccd..8c9af64bb9e01fd4bfe9511e9024117bcce3e8e8 100644
--- a/sdk/lib/async/stream_impl.dart
+++ b/sdk/lib/async/stream_impl.dart
@@ -145,7 +145,9 @@ class _BufferingStreamSubscription<T> implements StreamSubscription<T>,
 
   void onError(Function handleError) {
     if (handleError == null) handleError = _nullErrorHandler;
-    _onError = _registerErrorHandler/*<T>*/(handleError, _zone);
+    // We are not allowed to use 'void' as type argument for the generic type,
+    // so we use 'dynamic' instead.
+    _onError = _registerErrorHandler/*<dynamic>*/(handleError, _zone);
   }
 
   void onDone(void handleDone()) {