Clean up a bunch of our Dart code.

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

Index: sky/sdk/lib/framework/components2/button_base.dart
diff --git a/sky/sdk/lib/framework/components2/button_base.dart b/sky/sdk/lib/framework/components2/button_base.dart
index ca00617d4d85d80b0e2c6439e8c408ab50c6bebd..8e507f5adc82b03f829cb818abe6d4cedaf83ec1 100644
--- a/sky/sdk/lib/framework/components2/button_base.dart
+++ b/sky/sdk/lib/framework/components2/button_base.dart
@@ -5,7 +5,6 @@
 import '../fn2.dart';
 
 abstract class ButtonBase extends Component {
-  bool highlight = false;
 
   ButtonBase({ Object key }) : super(key: key);
 
@@ -20,6 +19,8 @@ abstract class ButtonBase extends Component {
     );
   }
 
+  bool highlight = false;
+
   void _handlePointerDown(_) {
     setState(() {
       highlight = true;