Use package:sky imports consistently

sky/sdk/lib/widgets/menu_item.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 '../painting/text_style.dart';
-import 'basic.dart';
-import 'button_base.dart';
-import 'default_text_style.dart';
-import 'icon.dart';
-import 'ink_well.dart';
-import 'theme.dart';
-import 'widget.dart';
+import 'package:sky/painting/text_style.dart';
+import 'package:sky/widgets/basic.dart';
+import 'package:sky/widgets/button_base.dart';
+import 'package:sky/widgets/default_text_style.dart';
+import 'package:sky/widgets/icon.dart';
+import 'package:sky/widgets/ink_well.dart';
+import 'package:sky/widgets/theme.dart';
+import 'package:sky/widgets/widget.dart';
 
 const BoxDecoration _kHighlightDecoration = const BoxDecoration(
   backgroundColor: const Color.fromARGB(102, 153, 153, 153)
 );
 
 // TODO(abarth): We shouldn't need _kHighlightBoring, but currently Container
 //               isn't smart enough to retain the components it builds when we
 //               add or remove a |decoration|. For now, we use a transparent
 //               decoration to avoid changing the structure of the tree. The
 //               right fix, however, is to make Container smarter about how it
@@ skipping 61 matching lines @@
         child: new Container(
           decoration: highlight ? _kHighlightDecoration : _kHighlightBoring,
           child: new InkWell(
             child: new Flex(flexChildren)
           )
         )
       )
     );
   }
 }