Use package:sky imports consistently

sky/sdk/lib/widgets/icon_button.dart

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 import 'dart:sky' as sky;
 
-import '../rendering/box.dart';
-import 'basic.dart';
-import 'icon.dart';
-import 'widget.dart';
+import 'package:sky/rendering/box.dart';
+import 'package:sky/widgets/basic.dart';
+import 'package:sky/widgets/icon.dart';
+import 'package:sky/widgets/widget.dart';
 
 class IconButton extends Component {
 
   IconButton({ String icon: '', this.onPressed, this.color })
     : super(key: icon), icon = icon;
 
   final String icon;
   final Function onPressed;
   final Color color;
 
@@ skipping 11 matching lines @@
         child: child,
         padding: const EdgeDims.all(8.0)),
       onGestureTap: (_) {
         if (onPressed != null)
           onPressed();
       }
     );
   }
 
 }