Update Button to be made of Material

sky/framework/components/input.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 '../editing/editable_string.dart';
 import '../editing/editable_text.dart';
 import '../editing/keyboard.dart';
 import '../fn.dart';
 import '../theme/colors.dart';
 
@@ skipping 57 matching lines @@
   Node build() {
     if (focused && !_isAttachedToKeyboard) {
       keyboard.show(_editableValue.stub);
       _isAttachedToKeyboard = true;
     }
 
     List<Node> children = [];
 
     if (placeholder != null && _value.isEmpty) {
       children.add(new Container(
-          style: _placeholderStyle,
+          styles: [_placeholderStyle],
           children: [new Text(placeholder)]
       ));
     }
 
     children.add(new EditableText(value: _editableValue, focused: focused));
 
     return new Container(
-      style: _style,
+      styles: [_style],
       inlineStyle: focused ? _focusedInlineStyle : null,
       children: children
     );
   }
 }