Make it possible to construct a Stock directly

sky/examples/stocks-fn/lib/stock_data.dart

 // Copyright 2014 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:convert';
 import 'dart:math';
 import 'package:sky/framework/net/fetch.dart';
 
 // Snapshot from http://www.nasdaq.com/screening/company-list.aspx
 // Fetched 2/23/2014.
 // "Symbol","Name","LastSale","MarketCap","IPOyear","Sector","industry","Summary Quote",
 // final List<List<String>> _kCompanyList = [
 //   ["TFSC","1347 Capital Corp.","9.43","\$56.09M","2014","Finance","Business Services","http://www.nasdaq.com/symbol/tfsc"],
 //   ["TFSCR","1347 Capital Corp.","0.37","n/a","2014","Finance","Business Services","http://www.nasdaq.com/symbol/tfscr"],
 //   ["TFSCU","1347 Capital Corp.","9.97","\$41.67M","2014","n/a","n/a","http://www.nasdaq.com/symbol/tfscu"],
 //   ["TFSCW","1347 Capital Corp.","0.2","n/a","2014","Finance","Business Services","http://www.nasdaq.com/symbol/tfscw"],
 // ];
 
 class Stock {
   String symbol;
   String name;
   double lastSale;
   String marketCap;
   double percentChange;
 
-  Stock(this.symbol, this.name, this.lastSale, this.marketCap);
+  Stock(this.symbol, this.name, this.lastSale, this.marketCap, this.percentChange);
 
   Stock.fromFields(List<String> fields) {
     // FIXME: This class should only have static data, not lastSale, etc.
     // "Symbol","Name","LastSale","MarketCap","IPOyear","Sector","industry","Summary Quote",
     lastSale = 0.0;
     try{
       lastSale = double.parse(fields[2]);
     } catch(_) {}
     symbol = fields[0];
     name = fields[1];
@@ skipping 21 matching lines @@
   }
 }
 
 Future<StockOracle> fetchStockOracle() async {
   Response response = await fetch('lib/stock_data.json');
   String json = response.bodyAsString();
   JsonDecoder decoder = new JsonDecoder();
   var companyList = decoder.convert(json);
   return new StockOracle.fromCompanyList(companyList);
 }