Refactoring to support dark theme better

sky/sdk/home.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';
 
 import 'package:mojom/intents/intents.mojom.dart';
 import 'package:sky/mojo/shell.dart' as shell;
 import 'package:sky/painting/box_painter.dart';
 import 'package:sky/theme/colors.dart' as colors;
-import 'package:sky/theme/edges.dart';
 import 'package:sky/theme/typography.dart' as typography;
 import 'package:sky/widgets/basic.dart';
 import 'package:sky/widgets/card.dart';
 import 'package:sky/widgets/fixed_height_scrollable.dart';
 import 'package:sky/widgets/flat_button.dart';
 import 'package:sky/widgets/material.dart';
 import 'package:sky/widgets/scaffold.dart';
 import 'package:sky/widgets/theme.dart';
 import 'package:sky/widgets/tool_bar.dart';
 
@@ skipping 141 matching lines @@
       .skip(start)
       .take(count)
       .map(buildDemo)
       .toList(growable: false);
   }
 }
 
 class SkyHome extends App {
   Widget build() {
     return new Theme(
-      data: new ThemeData.dark(
-        primary: colors.Teal,
-        accent: colors.Orange
+      data: new ThemeData(
+        brightness: ThemeBrightness.dark,
+        primarySwatch: colors.Teal
       ),
       child: new Scaffold(
         toolbar: new ToolBar(center: new Text('Sky Demos')),
         body: new Material(
-          edge: MaterialEdge.canvas,
+          type: MaterialType.canvas,
           child: new DemoList()
         )
       )
     );
   }
 }
 
 void main() {
   runApp(new SkyHome());
 }