Show the last sale price in the stocks app

sky/examples/stocks/stock.sky

 <!--
 // 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 src="/sky/framework/sky-element.sky" />
 
-<sky-element attributes="ticker:string">
+<sky-element>
 <template>
   <style>
   :host {
     height: 50px;
     display: flex;
     width: 100%;
     border: 1px solid black;
   }
   #ticker {
     padding: 10px;
     flex-grow: 1;
   }
+  #last-sale {
+    padding: 10px;
+  }
   #change {
     padding: 10px;
     border-radius: 5px;
-    min-width: 60px;
+    min-width: 70px;
     text-align: right;
   }
   .positive {
     background-color: green;
   }
   .negative {
     background-color: red;
   }
   </style>
   <div id="ticker" />
+  <div id="last-sale" />
   <div id="change" />
 </template>
 <script>
 import "dart:sky";
 
 @Tagname('stock')
 class Stock extends SkyElement {
   var model; // model.Stock
 
   void shadowRootReady() {
-    Element ticker = shadowRoot.getElementById('ticker');
-    ticker.textContent = model.symbol;
+    shadowRoot.getElementById('ticker').textContent = model.symbol;
+
+    Element lastSale = shadowRoot.getElementById('last-sale');
+    lastSale.textContent = "\$${model.lastSale.toStringAsFixed(2)}";
 
     Element change = shadowRoot.getElementById('change');
-    change.textContent = "${model.percentChange.toStringAsFixed(2)}%";
+    String changeString = "${model.percentChange.toStringAsFixed(2)}%";
+    if (model.percentChange > 0)
+      changeString = "+" + changeString;
+    change.textContent = changeString;
     change.classList.add((model.percentChange < 0) ? 'negative' : 'positive');
   }
 }
 
 _init(script) => register(script, Stock);
 </script>
 </sky-element>