Introduce Scaffold to Sky framework

sky/framework/components/drawer.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 'animated_component.dart';
 import '../animation/animated_value.dart';
 import '../animation/curves.dart';
 import '../fn.dart';
 import '../theme/colors.dart';
 import '../theme/shadows.dart';
@@ skipping 58 matching lines @@
 
     double targetPosition = direction < 0.0 ? -_kWidth : 0.0;
     double distance = (targetPosition - position.value).abs();
     double duration = distance / velocityX;
 
     position.animateTo(targetPosition, duration, curve: linear);
   }
 }
 
 class Drawer extends AnimatedComponent {
+  // TODO(abarth): We need a better way to become a container for absolutely
+  // positioned elements.
   static final Style _style = new Style('''
-    position: absolute;
-    top: 0;
-    left: 0;
-    bottom: 0;
-    right: 0;'''
-  );
+    transform: translateX(0);''');
 
   static final Style _maskStyle = new Style('''
     background-color: black;
     will-change: opacity;
     position: absolute;
     top: 0;
     left: 0;
     bottom: 0;
     right: 0;'''
   );
@@ skipping 53 matching lines @@
         inlineStyle: inlineStyle,
         children: [ mask, content ]
       ),
       onPointerDown: controller.handlePointerDown,
       onPointerMove: controller.handlePointerMove,
       onPointerUp: controller.handlePointerUp,
       onPointerCancel: controller.handlePointerCancel
     );
   }
 }