Change singleSubscription/multiSubscription to normal/broadcast.

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 a0a30b0095007adf77542dc67752e0504bae1d4c..5d59bb4bd13962915859e01240219d2ec43aba93 100644
--- a/sdk/lib/isolate/isolate_stream.dart
+++ b/sdk/lib/isolate/isolate_stream.dart
@@ -95,10 +95,10 @@ class IsolateStream extends Stream<dynamic> {
                             { void onError(AsyncError error),
                               void onDone(),
                               bool unsubscribeOnError}) {
-      return _controller.listen(onData,
-                                onError: onError,
-                                onDone: onDone,
-                                unsubscribeOnError: unsubscribeOnError);
+      return _controller.stream.listen(onData,
+                                       onError: onError,
+                                       onDone: onDone,
+                                       unsubscribeOnError: unsubscribeOnError);
   }
 
   dynamic _unmangleMessage(var message) {