Redo StreamTransformers so they work with Stack traces.

tests/lib/async/catch_errors23_test.dart

Index: tests/lib/async/catch_errors23_test.dart
diff --git a/tests/lib/async/catch_errors23_test.dart b/tests/lib/async/catch_errors23_test.dart
index cb78b3dbcf08c899640532cd72d181a99495a1c2..46451753ee5f402c533dae135439090d3ced096f 100644
--- a/tests/lib/async/catch_errors23_test.dart
+++ b/tests/lib/async/catch_errors23_test.dart
@@ -25,8 +25,8 @@ main() {
           events.add("map $x");
           return x + 100;
         })
-        .transform(new StreamTransformer(
-            handleError: (e, sink) => sink.add("error $e")))
+        .transform(new StreamTransformer.fromHandlers(
+            handleError: (e, st, sink) => sink.add("error $e")))
         .asBroadcastStream();
       stream.listen((x) { events.add("stream $x"); });
     }).listen((x) { events.add(x); })