Make it harder to forget itemCount for FixedHeightScrollable

sky/sdk/example/stocks/lib/stock_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 'package:sky/editing/input.dart';
 import 'package:sky/widgets/basic.dart';
 import 'package:sky/widgets/drawer.dart';
 import 'package:sky/widgets/drawer_header.dart';
 import 'package:sky/widgets/floating_action_button.dart';
 import 'package:sky/widgets/icon.dart';
@@ skipping 146 matching lines @@
      ]
     );
   }
 
   void _handleOpenDrawer() {
     _drawerController.open();
     navigator.pushState("/drawer", (_) {
       _drawerController.close();
     });
   }
-  
+
   Widget buildToolBar() {
     return new ToolBar(
         left: new IconButton(
           icon: 'navigation/menu_white',
           onPressed: _handleOpenDrawer),
         center: new Text('Stocks'),
         right: [
           new IconButton(
             icon: 'action/search_white',
             onPressed: _handleSearchBegin),
           new IconButton(
             icon: 'navigation/more_vert_white',
             onPressed: _handleMenuShow)
         ]
       );
   }
 
   int selectedTabIndex = 0;
   List<String> portfolioSymbols = ["AAPL","FIZZ", "FIVE", "FLAT", "ZINC", "ZNGA"];
 
+  Iterable<Stock> _filterByPortfolio(Iterable<Stock> stocks) {
+    return stocks.where((stock) => portfolioSymbols.contains(stock.symbol));
+  }
+
+  Iterable<Stock> _filterBySearchQuery(Iterable<Stock> stocks) {
+    if (_searchQuery == null)
+      return stocks;
+    RegExp regexp = new RegExp(_searchQuery, caseSensitive: false);
+    return stocks.where((stock) => stock.symbol.contains(regexp));
+  }
+
+  Widget buildMarketStockList() {
+    return new Stocklist(stocks: _filterBySearchQuery(stocks).toList());
+  }
+
   Widget buildPortfolioStocklist() {
-    return new Stocklist(
-     stocks: stocks.where((s) => portfolioSymbols.contains(s.symbol)).toList(), 
-     query: _searchQuery
-   );
+    return new Stocklist(stocks: _filterBySearchQuery(_filterByPortfolio(stocks)).toList());
   }
 
   Widget buildTabNavigator() {
     List<TabNavigatorView> views = <TabNavigatorView>[
       new TabNavigatorView(
         label: const TabLabel(text: 'MARKET'),
-        builder: () => new Stocklist(stocks: stocks, query: _searchQuery)
+        builder: buildMarketStockList
       ),
       new TabNavigatorView(
         label: const TabLabel(text: 'PORTFOLIO'),
         builder: buildPortfolioStocklist
       )
     ];
     return new TabNavigator(
       views: views,
       selectedIndex: selectedTabIndex,
       onChanged: (tabIndex) {
@@ skipping 63 matching lines @@
         body: buildTabNavigator(),
         snackBar: buildSnackBar(),
         floatingActionButton: buildFloatingActionButton(),
         drawer: _drawerShowing ? buildDrawer() : null
       ),
     ];
     addMenuToOverlays(overlays);
     return new Stack(overlays);
   }
 }