Remove the |style| parameter from Material

sky/framework/components/material.dart

Index: sky/framework/components/material.dart
diff --git a/sky/framework/components/material.dart b/sky/framework/components/material.dart
index 245394cae6c05413e4b26a4f93d1417e713dc317..38eeb583579773a8e48ff8b2feec02eab697c5ef 100644
--- a/sky/framework/components/material.dart
+++ b/sky/framework/components/material.dart
@@ -16,21 +16,20 @@ class Material extends Component {
     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]);
   }
 }