Migrate async tests to strong

tests/lib_strong/async/run_zoned6_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:expect/expect.dart";
+import 'dart:async';
+import 'package:async_helper/async_helper.dart';
+
+main() {
+  asyncStart();
+  // Ensure that `runZoned`'s onError handles synchronous errors but delegates
+  // to the top-level when the handler returns false.
+  try {
+    runZoned(() {
+      throw 0;
+    }, onError: (e) {
+      Expect.equals(0, e);
+               if (false) //# 01: runtime error
+      asyncEnd();
+               throw e; //# 01: runtime error
+    });
+  } catch (e) {
+    // We should never see an error here.
+    if (false) //# 01: continued
+    rethrow;
+  }
+}