Fix all the components to pick the right colours from the theme.

sky/sdk/example/widgets/tabs.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 'package:sky/painting/text_style.dart';
 import 'package:sky/theme/typography.dart';
 import 'package:sky/widgets/basic.dart';
 import 'package:sky/widgets/material.dart';
 import 'package:sky/widgets/scaffold.dart';
 import 'package:sky/widgets/tabs.dart';
 import 'package:sky/widgets/tool_bar.dart';
 import 'package:sky/widgets/widget.dart';
 
 class TabbedNavigatorApp extends App {
   int selectedIndex = 0;
 
   Widget _buildContent(String label) {
     return new Center(
-      child: new Text(label, style: const TextStyle(fontSize: 48.0, fontWeight: extraBold))
+      child: new Text(label, style: const TextStyle(fontSize: 48.0, fontWeight: FontWeight.w800))
     );
   }
 
   Widget build() {
     List<TabNavigatorView> views = <TabNavigatorView>[
       new TabNavigatorView(
         label: const TabLabel(text: 'STOCKS', icon: 'action/list_white'),
         builder: () => _buildContent("Stocks")
       ),
       new TabNavigatorView(
@@ skipping 21 matching lines @@
     return new Scaffold(
       toolbar: toolbar,
       body: new Material(child: tabNavigator)
     );
   }
 }
 
 void main() {
   runApp(new TabbedNavigatorApp());
 }