Add support for line-height in TextStyle.

sky/examples/widgets/styled_text.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/rendering/box.dart';
 import 'package:sky/rendering/flex.dart';
 import 'package:sky/rendering/sky_binding.dart';
 import 'package:sky/theme/colors.dart';
 import 'package:sky/theme/theme_data.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/theme.dart';
 import 'package:sky/widgets/tool_bar.dart';
 import 'package:sky/widgets/widget.dart';
 
 
 class StyledTextApp extends App {
 
@@ skipping 14 matching lines @@
 Dave: Open the pod bay doors, HAL.
 HAL: I'm sorry, Dave. I'm afraid I can't do that.
 Dave: What's the problem?
 HAL: I think you know what the problem is just as well as I do.
 Dave: What are you talking about, HAL?
 HAL: This mission is too important for me to allow you to jeopardize it.''';
 
   // [["Dave", "Open the pod bay..."] ...]
   List<List<String>> nameLines;
 
-  final TextStyle daveStyle = new TextStyle(color: Indigo[400]);
+  final TextStyle daveStyle = new TextStyle(color: Indigo[400], height: 1.8);
   final TextStyle halStyle = new TextStyle(color: Red[400], fontFamily: "monospace");
   final TextStyle boldStyle = const TextStyle(fontWeight: bold);
   final TextStyle underlineStyle = const TextStyle(
     decoration: underline,
     decorationColor: const Color(0xFF000000),
     decorationStyle: TextDecorationStyle.wavy
   );
   
   Component toStyledText(String name, String text) {
     TextStyle lineStyle = (name == "Dave") ? daveStyle : halStyle;
@@ skipping 62 matching lines @@
   }
 }
 
 void main() {
   runApp(new StyledTextApp());
   SkyBinding.instance.onFrame = () {
     // uncomment this for debugging:
     // SkyBinding.instance.debugDumpRenderTree();
   };
 }