Remove one more use of mirrors: Components now have to explicitly sync their fields.

sky/examples/stocks2/lib/stock_menu.dart

Index: sky/examples/stocks2/lib/stock_menu.dart
diff --git a/sky/examples/stocks2/lib/stock_menu.dart b/sky/examples/stocks2/lib/stock_menu.dart
index c4e261d34c59084be28b0805e9892d245a416f28..b0d40a72c6beaaf8ced12facefa438505f12e497 100644
--- a/sky/examples/stocks2/lib/stock_menu.dart
+++ b/sky/examples/stocks2/lib/stock_menu.dart
@@ -8,10 +8,15 @@ import 'package:sky/framework/components2/checkbox.dart';
 import 'package:sky/framework/theme/view_configuration.dart';
 
 class StockMenu extends Component {
-  PopupMenuController controller;
 
-  StockMenu({Object key, this.controller, this.autorefresh: false, this.onAutorefreshChanged}) : super(key: key);
+  StockMenu({
+    Object key,
+    this.controller,
+    this.autorefresh: false,
+    this.onAutorefreshChanged
+  }) : super(key: key);
 
+  final PopupMenuController controller;
   final bool autorefresh;
   final ValueChanged onAutorefreshChanged;