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

sky/sdk/lib/framework/components2/tool_bar.dart

Index: sky/sdk/lib/framework/components2/tool_bar.dart
diff --git a/sky/sdk/lib/framework/components2/tool_bar.dart b/sky/sdk/lib/framework/components2/tool_bar.dart
index a90afed8080df4842319d736c86d6ea9ecaaea70..207027531198d9827764bff3260a628bb2a8b4be 100644
--- a/sky/sdk/lib/framework/components2/tool_bar.dart
+++ b/sky/sdk/lib/framework/components2/tool_bar.dart
@@ -21,6 +21,14 @@ class ToolBar extends Component {
   List<UINode> right;
   Color backgroundColor;
 
+  void syncFields(ToolBar source) {
+    left = source.left;
+    center = source.center;
+    right = source.right;
+    backgroundColor = source.backgroundColor;
+    super.syncFields(source);
+  }
+
   UINode build() {
     List<UINode> children = [
       left,