Add Material light and dark themes to Sky widgets

R=ianh@google.com, hixie

Review URL: https://codereview.chromium.org/1204523002.

examples/stocks2/lib/stock_app.dart

@@ -5,7 +5,6 @@
 import 'package:sky/rendering/sky_binding.dart';
 import 'package:sky/theme/colors.dart' as colors;
 import 'package:sky/theme/theme_data.dart';
-import 'package:sky/theme/typography.dart' as typography;
 import 'package:sky/widgets/basic.dart';
 import 'package:sky/widgets/navigator.dart';
 import 'package:sky/widgets/theme.dart';
@@ -51,7 +50,10 @@ class StocksApp extends App {
 
   Widget build() {
     return new Theme(
-      data: new ThemeData(color: colors.Purple, text: typography.white),
+      data: new ThemeData.light(
+        primary: colors.Purple,
+        accent: colors.RedAccent,
+        darkToolbar: true),
       child: new Navigator(_navigationState)
     );
   }

examples/stocks2/lib/stock_home.dart

@@ -4,7 +4,6 @@
 
 import 'package:sky/editing/input.dart';
 import 'package:sky/theme/colors.dart' as colors;
-import 'package:sky/theme/typography.dart' as typography;
 import 'package:sky/widgets/basic.dart';
 import 'package:sky/widgets/drawer.dart';
 import 'package:sky/widgets/drawer_header.dart';
@@ -161,7 +160,7 @@ class StockHome extends Component {
         left: new IconButton(
           icon: 'navigation/menu_white',
           onPressed: _handleOpenDrawer),
-        center: new Text('Stocks', style: typography.white.title),
+        center: new Text('Stocks'),
         right: [
           new IconButton(
             icon: 'action/search_white',

examples/stocks2/lib/stock_row.dart

@@ -4,9 +4,9 @@
 
 import 'package:sky/painting/text_style.dart';
 import 'package:sky/rendering/box.dart';
-import 'package:sky/theme/typography.dart' as typography;
 import 'package:sky/widgets/ink_well.dart';
 import 'package:sky/widgets/basic.dart';
+import 'package:sky/widgets/theme.dart';
 
 import 'stock_arrow.dart';
 import 'stock_data.dart';
@@ -43,7 +43,7 @@ class StockRow extends Component {
       new Flexible(
         child: new Text(
           changeInPrice,
-          style: typography.black.caption.copyWith(textAlign: TextAlign.right)
+          style: Theme.of(this).text.caption.copyWith(textAlign: TextAlign.right)
         )
       )
     ];

examples/widgets/sector.dart

@@ -77,10 +77,10 @@ class SectorApp extends App {
 
   Widget build() {
     return new Theme(
-      data: new ThemeData(color: colors.Blue, text: typography.white),
+      data: new ThemeData.light(primary: colors.Blue, darkToolbar: true),
       child: new Scaffold(
         toolbar: new ToolBar(
-            center: new Text('Sector Layout in a Widget Tree', style: typography.white.title)),
+            center: new Text('Sector Layout in a Widget Tree')),
         body: new Material(
           edge: MaterialEdge.canvas,
           child: new Flex([

examples/widgets/styled_text.dart

@@ -108,11 +108,11 @@ HAL: This mission is too important for me to allow you to jeopardize it.''';
     );
 
     return new Theme(
-      data: new ThemeData(color: Blue, text: white),
+      data: new ThemeData.light(primary: Blue, darkToolbar: true),
       child: new Scaffold(
         body: new Material(child: interactiveBody),
         toolbar: new ToolBar(
-          center: new Text('Hal and Dave', style: white.title)
+          center: new Text('Hal and Dave')
         )
       )
     );