Allow Effen Styles to be extendable

sky/examples/stocks-fn/stocksapp.dart

 library stocksapp;
 
 import '../../framework/fn.dart';
 import '../../framework/animation/scroll_behavior.dart';
 import '../../framework/components/drawer.dart';
 import '../../framework/components/drawer_header.dart';
 import '../../framework/components/fixed_height_scrollable.dart';
 import '../../framework/components/floating_action_button.dart';
 import '../../framework/components/icon.dart';
 import '../../framework/components/input.dart';
@@ skipping 87 matching lines @@
     Node title;
     if (_isSearching) {
       title = new Input(focused: true, placeholder: 'Search stocks',
           onChanged: _handleSearchQueryChanged);
     } else {
       title = new Text('I am a stocks app');
     }
 
     var toolbar = new Toolbar(
       children: [
-        new Icon(key: 'menu', styles: [_iconStyle],
+        new Icon(key: 'menu', style: _iconStyle,
             size: 24,
             type: 'navigation/menu_white')
           ..events.listen('click', _drawerAnimation.toggle),
         new Container(
-          styles: [_titleStyle],
+          style: _titleStyle,
           children: [title]
         ),
-        new Icon(key: 'search', styles: [_iconStyle],
+        new Icon(key: 'search', style: _iconStyle,
             size: 24,
             type: 'action/search_white')
           ..events.listen('click', _handleSearchClick),
-        new Icon(key: 'more_white', styles: [_iconStyle],
+        new Icon(key: 'more_white', style: _iconStyle,
             size: 24,
             type: 'navigation/more_vert_white')
       ]
     );
 
     var list = new Stocklist(stocks: _sortedStocks, query: _searchQuery);
 
     var fab = new FloatingActionButton(content: new Icon(
       type: 'content/add_white', size: 24), level: 3);
 
     return new Container(
       key: 'StocksApp',
       children: [
         new Container(
           key: 'Content',
-          styles: [_style],
+          style: _style,
           children: [toolbar, list]
         ),
         fab,
         drawer,
       ]
     );
   }
 }