Execute callbacks from JS in the correct zone

tests/html/js_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.
 
 library jsTest;
 
 import 'dart:async';
 import 'dart:html';
 import 'dart:typed_data' show ByteBuffer, Int32List;
 import 'dart:indexed_db' show IdbFactory, KeyRange;
@@ skipping 641 matching lines @@
   group('Dart functions', () {
     test('invoke Dart callback from JS', () {
       expect(() => context.callMethod('invokeCallback'), throws);
 
       context['callback'] = () => 42;
       expect(context.callMethod('invokeCallback'), equals(42));
 
       context.deleteProperty('callback');
     });
 
+    test('invoke Dart callback from JS in a Zone', () {
+      expect(() => context.callMethod('invokeCallback'), throws);
+
+      var childZone = Zone.current.fork();
+      childZone.run(() {
+        context['callback'] = () {
+          expect(Zone.current, childZone);
+        };
+      });
+      context.callMethod('invokeCallback');
+
+      context.deleteProperty('callback');
+    });
+
     test('callback as parameter', () {
       expect(context.callMethod('getTypeOf', [context['razzle']]),
           equals("function"));
     });
 
     test('invoke Dart callback from JS with this', () {
       // A JavaScript constructor function implemented in Dart which
       // uses 'this'
       final constructor = new JsFunction.withThis(($this, arg1) {
         var t = $this;
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           // expect(context.callMethod('isPropertyInstanceOf', ['o', listType]),
           //    isTrue);
           context.deleteProperty('o');
         }
       });
 
     });
   });
 
 }