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

tests/isolate/issue_21398_parent_isolate_test.dart

Index: tests/isolate/issue_21398_parent_isolate_test.dart
diff --git a/tests/isolate/issue_21398_parent_isolate_test.dart b/tests/isolate/issue_21398_parent_isolate_test.dart
index fb4b0fb6fd0ba3a7a44de11c89cb74ae1956a4d2..76e7e0d4436b57a3762453270ec48b04215e6650 100644
--- a/tests/isolate/issue_21398_parent_isolate_test.dart
+++ b/tests/isolate/issue_21398_parent_isolate_test.dart
@@ -9,6 +9,7 @@
 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';
@@ -29,13 +30,16 @@ main() {
 
   // 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(
@@ -44,6 +48,7 @@ main() {
         (msg) {
           Expect.stringEquals(msg, "Invalid Argument(s).");
           receive1.close();
+          asyncEnd();
         },
         onError: (e) => print('$e')
       );
@@ -53,7 +58,8 @@ main() {
   // Now spawn an isolate using spawnFunction and send it a "non-literal"
   // like object and also have the child isolate send back a "non-literal"
   // like object.
-  Isolate.spawn(funcChild, 
+  asyncStart();
+  Isolate.spawn(funcChild,
                 [new FromMainIsolate(), receive2.sendPort]).then(
     (isolate) {
       receive2.listen(
@@ -61,6 +67,7 @@ main() {
           Expect.isTrue(msg is FromMainIsolate);
           Expect.equals(10, msg.fld);
           receive2.close();
+          asyncEnd();
         },
         onError: (e) => print('$e')
       );