Migrate async tests to strong

tests/lib_strong/async/catch_errors16_test.dart

+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:async_helper/async_helper.dart';
+import "package:expect/expect.dart";
+import 'dart:async';
+import 'catch_errors.dart';
+
+main() {
+  asyncStart();
+  var events = [];
+  StreamController controller = new StreamController();
+  Stream stream = controller.stream;
+  // Test that the subscription of a stream is what counts. The error (2) runs
+  // through the map-stream which goes through the nested `catchError` but
+  // the nested `catchError` won't see the error.
+  catchErrors(() {
+    stream = stream.map((x) => x + 100);
+  }).listen((x) { events.add(x); });
+  stream
+    .transform(new StreamTransformer.fromHandlers(
+        handleError: (e, st, sink) { sink.add("error $e"); }))
+    .listen((x) { events.add("stream $x"); },
+            onDone: () {
+              Expect.listEquals(["stream 101",
+                                "stream error 2",
+                                ],
+                                events);
+              asyncEnd();
+            });
+  controller.add(1);
+  controller.addError(2);
+  controller.close();
+}