Add zone support to streams.

tests/lib/async/catch_errors18_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 'dart:isolate';
 
 main() {
   // We keep a ReceivePort open until all tests are done. This way the VM will
   // 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.
+  Stream stream = new Stream.periodic(const Duration(milliseconds: 20),
+                                      (x) => x);
+  // Test that errors of periodic streams are caught.
   catchErrors(() {
-    events.add("catch error entry");
-    throw "catch error";
-  }).listen((x) {
+    var subscription;
+    subscription = stream.listen((x) {
+      if (x == 5) {
+        events.add("cancel");
+        subscription.cancel();
+        return;
+      }
       events.add(x);
-    },
-    onDone: () {
-      Expect.listEquals(["catch error entry",
-                         "main exit",
-                         "catch error",
-                         ],
-                         events);
-      port.close();
     });
-  events.add("main exit");
+  }).listen((x) { events.add("outer: $x"); },
+            onDone: () {
+              Expect.listEquals([0, 1, 2, 3, 4, "cancel"], events);
+              port.close();
+            });
 }