Migrated test block 167 to Dart 2.0.

tests/lib/async/catch_errors20_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();
-  Completer done = new Completer();
-
-  var events = [];
-  // Test that nested stream (from `catchErrors`) that is delayed by a future
-  // is waited for.
-  catchErrors(() {
-    catchErrors(() {
-      new Future.error(499);
-      new Future.delayed(const Duration(milliseconds: 20), () {
-        events.add(42);
-        done.complete(true);
-      });
-    }).listen(events.add, onDone: () {
-      events.add("done");
-    });
-    throw "foo";
-  }).listen((x) {
-    events.add("outer: $x");
-  }, onDone: () {
-    Expect.fail("Unexpected callback");
-  });
-
-  done.future.whenComplete(() {
-    // Give handlers time to run.
-    Timer.run(() {
-      Expect.listEquals([
-        "outer: foo",
-        499,
-        42,
-      ], events);
-      asyncEnd();
-    });
-  });
-}