Use package:sky imports consistently

sky/sdk/lib/theme/typography.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.
 
 // See http://www.google.com/design/spec/style/typography.html
 
 import 'dart:sky';
 
-import '../painting/text_style.dart';
+import 'package:sky/painting/text_style.dart';
 
 // TODO(eseidel): Font weights are supposed to be language relative!
 // These values are for English-like text.
 class TextTheme {
   TextTheme._(Color color54, Color color87)
     : display4 = new TextStyle(fontSize: 112.0, fontWeight: FontWeight.w100, color: color54),
       display3 = new TextStyle(fontSize:  56.0, fontWeight: FontWeight.w400, color: color54),
       display2 = new TextStyle(fontSize:  45.0, fontWeight: FontWeight.w400, color: color54, height: 48.0 / 45.0),
       display1 = new TextStyle(fontSize:  34.0, fontWeight: FontWeight.w400, color: color54, height: 40.0 / 34.0),
       headline = new TextStyle(fontSize:  24.0, fontWeight: FontWeight.w400, color: color87, height: 32.0 / 24.0),
@@ skipping 35 matching lines @@
 const TextStyle error = const TextStyle(
   color: const Color(0xD0FF0000),
   fontFamily: 'monospace',
   fontSize: 48.0,
   fontWeight: FontWeight.w900,
   textAlign: TextAlign.right,
   decoration: underline,
   decorationColor: const Color(0xFFFF00),
   decorationStyle: TextDecorationStyle.double
 );
-