Execute callbacks from JS in the correct zone

sdk/lib/js/dartium/js_dartium.dart

Index: sdk/lib/js/dartium/js_dartium.dart
diff --git a/sdk/lib/js/dartium/js_dartium.dart b/sdk/lib/js/dartium/js_dartium.dart
index e7f3004c686d8efbc0b5bdc038bbb28178f2f5d2..69f272d20c93b2ea0d0cdbc0ac6d8c383f5b48e0 100644
--- a/sdk/lib/js/dartium/js_dartium.dart
+++ b/sdk/lib/js/dartium/js_dartium.dart
@@ -87,6 +87,7 @@
  */
 library dart.js;
 
+import 'dart:async' show Zone;
 import 'dart:collection' show ListMixin;
 import 'dart:nativewrappers';
 
@@ -360,6 +361,18 @@ class JsArray<E> extends JsObject with ListMixin<E> {
 }
 
 /**
+ * This function performs any wrapping of a Dart value before Dartium proxies
+ * it to JS.
+ */
+_wrapToJs(value) => value is Function ? _applyZoned(value) : value;
+
+_applyZoned(f) {
+  var call = (List arguments) => Function.apply(f, arguments);
+  if (Zone.current == Zone.ROOT) return call;
+  return Zone.current.bindUnaryCallback(call);
+}
+
+/**
  * Placeholder object for cases where we need to determine exactly how many
  * args were passed to a function.
  */