Change the name of Component.render to Component.build in Effen

sky/examples/fn/widgets/menudivider.dart

 part of widgets;
 
 class MenuDivider extends Component {
 
   static Style _style = new Style('''
     margin: 8px 0;
     border-bottom: 1px solid rgba(0, 0, 0, 0.12);'''
   );
 
   MenuDivider({ Object key }) : super(key: key);
 
-  Node render() {
+  Node build() {
     return new Container(
       style: _style
     );
   }
 }