Use package:sky imports consistently

sky/sdk/lib/widgets/toggleable.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 '../animation/animation_performance.dart';
-import '../animation/curves.dart';
-import 'animated_component.dart';
-import 'basic.dart';
+import 'package:sky/animation/animation_performance.dart';
+import 'package:sky/animation/curves.dart';
+import 'package:sky/widgets/animated_component.dart';
+import 'package:sky/widgets/basic.dart';
 
 typedef void ValueChanged(value);
 
 const Duration _kCheckDuration = const Duration(milliseconds: 200);
 
 abstract class Toggleable extends AnimatedComponent {
 
   Toggleable({
     String key,
     this.value,
@@ skipping 55 matching lines @@
         height: size.height,
         child: new CustomPaint(
           token: position.value,
           callback: customPaintCallback
         )
       ),
       onGestureTap: _handleClick
     );
   }
 }