Add Zone support for Timers.

tests/lib/async/catch_errors28_test.dart

Index: tests/lib/async/catch_errors28_test.dart
diff --git a/tests/lib/async/catch_errors4_test.dart b/tests/lib/async/catch_errors28_test.dart
similarity index 65%
copy from tests/lib/async/catch_errors4_test.dart
copy to tests/lib/async/catch_errors28_test.dart
index d14f948911d101cfd7d8fb00e6ebcffc87981909..a5ce19e1270c89291333580070da82118a7f13b2 100644
--- a/tests/lib/async/catch_errors4_test.dart
+++ b/tests/lib/async/catch_errors28_test.dart
@@ -8,21 +8,24 @@ import 'dart:isolate';
 
 main() {
   // We keep a ReceivePort open until all tests are done. This way the VM will
-  // time out if the callbacks are not invoked.
+  // hang if the callbacks are not invoked and the test will time out.
   var port = new ReceivePort();
   var events = [];
-  // Test that synchronous errors inside a `catchErrors` are caught.
+  // Test that periodic Timers are handled correctly by `catchErrors`.
   catchErrors(() {
-    events.add("catch error entry");
-    throw "catch error";
+    int counter = 0;
+    new Timer.periodic(const Duration(milliseconds: 50), (timer) {
+      if (counter == 5) timer.cancel();
+      counter++;
+      events.add(counter);
+    });
   }).listen((x) {
       events.add(x);
     },
     onDone: () {
       Expect.listEquals([
-                         "catch error entry",
                          "main exit",
-                         "catch error",
+                         1, 2, 3, 4, 5, 6,
                          ],
                          events);
       port.close();