Stream isolates.

tests/corelib/stream_controller_test.dart

Index: tests/corelib/stream_controller_test.dart
diff --git a/tests/corelib/stream_controller_test.dart b/tests/corelib/stream_controller_test.dart
index 7e7333f8137532d882dab3b639aa4eecd00619e5..ad3cc670058374564ed25babb7c87dc0a2cfeaa4 100644
--- a/tests/corelib/stream_controller_test.dart
+++ b/tests/corelib/stream_controller_test.dart
@@ -255,4 +255,29 @@ main() {
     Expect.listEquals(expectedEvents.events, actualEvents.events);
   });
   signal.complete();
+
+  // Test subscription changes while firing.
+  c = new StreamController();
+  var sink = c.sink;
+  var stream = c.stream;
+  var counter = 0;
+  var subscription = stream.subscribe();
+  subscription.onData((data) {
+    counter += data;
+    subscription.unsubscribe();
+    stream.subscribe(onData: (data) {
+      counter += 10 * data;
+    });
+    var subscription2 = stream.subscribe();
+    subscription2.onData((data) {
+      counter += 100 * data;
+      if (data == 4) subscription2.unsubscribe();
+    });
+  });
+  sink.write(1); // seen by stream 1
+  sink.write(2); // seen by stream 10 and 100
+  sink.write(3); // -"-
+  sink.write(4); // -"-
+  sink.write(5); // seen by stream 10
+  Expect.equals(1 + 20 + 200 + 30 + 300 + 40 + 400 + 50, counter);
 }