Fix tests that don't catch asynchronous errors from isolate spawning. Update co19 status.

tests/isolate/issue_21398_parent_isolate_test.dart

 // Copyright (c) 2015, 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.
 
 // Note: the following comment is used by test.dart to additionally compile the
 // other isolate's code.
 // OtherScripts=issue_21398_child_isolate.dart
 
 import 'dart:isolate';
 import 'dart:async';
 import "package:expect/expect.dart";
+import 'package:async_helper/async_helper.dart';
 
 class FromMainIsolate {
   String toString() => 'from main isolate';
   int get fld => 10;
 }
 
 funcChild(args) {
   var reply = args[1];
   var obj = args[0];
   Expect.isTrue(obj is FromMainIsolate);
   Expect.equals(10, obj.fld);
   reply.send(new FromMainIsolate());
 }
 
 main() {
   var receive1 = new ReceivePort();
   var receive2 = new ReceivePort();
 
   // First spawn an isolate using spawnURI and have it
   // send back a "non-literal" like object.
+  asyncStart();
   Isolate.spawnUri(Uri.parse('issue_21398_child_isolate.dart'),
                    [],
                    [new FromMainIsolate(), receive1.sendPort]).catchError(
     (error) {
       Expect.isTrue(error is ArgumentError);
+      asyncEnd();
     }
   );
+  asyncStart();
   Isolate.spawnUri(Uri.parse('issue_21398_child_isolate.dart'),
                    [],
                    receive1.sendPort).then(
     (isolate) {
       receive1.listen(
         (msg) {
           Expect.stringEquals(msg, "Invalid Argument(s).");
           receive1.close();
+          asyncEnd();
         },
         onError: (e) => print('$e')
       );
     }
   );
 
   // Now spawn an isolate using spawnFunction and send it a "non-literal"
   // like object and also have the child isolate send back a "non-literal"
   // like object.
-  Isolate.spawn(funcChild, 
+  asyncStart();
+  Isolate.spawn(funcChild,
                 [new FromMainIsolate(), receive2.sendPort]).then(
     (isolate) {
       receive2.listen(
         (msg) {
           Expect.isTrue(msg is FromMainIsolate);
           Expect.equals(10, msg.fld);
           receive2.close();
+          asyncEnd();
         },
         onError: (e) => print('$e')
       );
     }
   );
 }