Remove the |style| parameter from Material

sky/framework/components/material.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 '../fn.dart';
 import '../theme/shadows.dart';
 import 'ink_well.dart';
 
 class Material extends Component {
   static final List<Style> shadowStyle = [
     null,
     new Style('box-shadow: ${Shadow[1]}'),
     new Style('box-shadow: ${Shadow[2]}'),
     new Style('box-shadow: ${Shadow[3]}'),
     new Style('box-shadow: ${Shadow[4]}'),
     new Style('box-shadow: ${Shadow[5]}'),
   ];
 
-  Style style;
   String inlineStyle;
   List<Node> children;
   int level;
 
   Material({
-      Object key,
-      this.style,
-      this.inlineStyle,
-      this.children,
-      this.level: 0 }) : super(key: key);
+    Object key,
+    this.inlineStyle,
+    this.children,
+    this.level: 0
+  }) : super(key: key);
 
   Node build() {
     return new StyleNode(
       new InkWell(inlineStyle: inlineStyle, children: children),
-      level > 0 ? style.extend(shadowStyle[level]) : style);
+      shadowStyle[level]);
   }
 }