Allow Effen Styles to be extendable

sky/examples/stocks-fn/stockrow.dart

 part of stocksapp;
 
 class StockRow extends Component {
 
   Stock stock;
 
   static Style _style = new Style('''
     transform: translateX(0);
     display: flex;
     align-items: center;
@@ skipping 29 matching lines @@
     String changeInPrice = "${stock.percentChange.toStringAsFixed(2)}%";
     if (stock.percentChange > 0)
       changeInPrice = "+" + changeInPrice;
 
     List<Node> children = [
       new StockArrow(
         percentChange: stock.percentChange
       ),
       new Container(
         key: 'Ticker',
-        styles: [_tickerStyle],
+        style: _tickerStyle,
         children: [new Text(stock.symbol)]
       ),
       new Container(
         key: 'LastSale',
-        styles: [_lastSaleStyle],
+        style: _lastSaleStyle,
         children: [new Text(lastSale)]
       ),
       new Container(
         key: 'Change',
-        styles: [_changeStyle],
+        style: _changeStyle,
         children: [new Text(changeInPrice)]
       )
     ];
 
     return new Material(
-      styles: [_style],
+      style: _style,
       children: children
     );
   }
 }