Expose Zones.

tests/lib/async/catch_errors12_test.dart

Index: tests/lib/async/catch_errors12_test.dart
diff --git a/tests/lib/async/catch_errors12_test.dart b/tests/lib/async/catch_errors12_test.dart
index af4acbc35819c5a7a07e3a853104f6c3a949b580..89528600a8addd2c95a24b7f8ae51a693e0fec15 100644
--- a/tests/lib/async/catch_errors12_test.dart
+++ b/tests/lib/async/catch_errors12_test.dart
@@ -9,6 +9,8 @@ import 'catch_errors.dart';
 
 main() {
   asyncStart();
+  Completer done = new Completer();
+
   var events = [];
   // Tests that errors that have been delayed by several milliseconds with
   // Timers are still caught by `catchErrors`.
@@ -17,13 +19,19 @@ main() {
     Timer.run(() { throw "timer error"; });
     new Timer(const Duration(milliseconds: 100), () { throw "timer2 error"; });
     new Future.value(499).then((x) {
-      new Timer(const Duration(milliseconds: 200), () { throw x; });
+      new Timer(const Duration(milliseconds: 200), () {
+        done.complete(499);
+        throw x;
+      });
     });
     throw "catch error";
   }).listen((x) {
       events.add(x);
     },
-    onDone: () {
+    onDone: () { Expect.fail("Unexpected callback"); });
+  done.future.whenComplete(() {
+    // Give time to execute the callbacks.
+    Timer.run(() {
       Expect.listEquals([
             "catch error entry",
             "main exit",
@@ -35,5 +43,6 @@ main() {
           events);
       asyncEnd();
     });
+  });
   events.add("main exit");
 }