[Effen] s/Node/UINode/, s/Element/WrapperNode/, s/EventTarget/EventListenerNode/

sky/framework/components/button.dart

Index: sky/framework/components/button.dart
diff --git a/sky/framework/components/button.dart b/sky/framework/components/button.dart
index 589253ab3d94cd61d6186ec2ac66ec32a77dc200..0544107b85d25f0961228ccebef792a4e79f11ed 100644
--- a/sky/framework/components/button.dart
+++ b/sky/framework/components/button.dart
@@ -19,12 +19,12 @@ class Button extends Component {
     border-radius: 2px;'''
   );
 
-  Node content;
+  UINode content;
   int level;
 
   Button({ Object key, this.content, this.level }) : super(key: key);
 
-  Node build() {
+  UINode build() {
     return new StyleNode(
       new Material(
         content: new InkWell(children: [content]),