Change singleSubscription/multiSubscription to normal/broadcast.

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 fb94f208090452aee7496f2cd71c8598f4852603..28c41b09804e7a687f9499462aff565652e2a6a2 100644
--- a/sdk/lib/async/stream_impl.dart
+++ b/sdk/lib/async/stream_impl.dart
@@ -544,9 +544,9 @@ class _MultiStreamImpl<T> extends _StreamImpl<T>
     _nextLink = _previousLink = this;
   }
 
-  bool get isSingleSubscription => false;
+  bool get isBroadcast => true;
 
-  Stream<T> asMultiSubscriberStream() => this;
+  Stream<T> asBroadcastStream() => this;
 
   // ------------------------------------------------------------------
   // Helper functions that can be overridden in subclasses.