Add a proper material shadow the popup menu

sky/sdk/lib/framework/components2/popup_menu.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 '../fn2.dart';
 import '../theme2/colors.dart';
+import '../theme2/shadows.dart';
+import 'animated_component.dart';
 import 'dart:async';
 import 'dart:math' as math;
 import 'material.dart';
 import 'popup_menu_item.dart';
 
 const double _kMenuOpenDuration = 300.0;
 const double _kMenuCloseDuration = 200.0;
 const double _kMenuCloseDelay = 100.0;
 
 enum MenuState { hidden, opening, open, closing }
@@ skipping 72 matching lines @@
   //   });
   // }
 
   UINode build() {
     int i = 0;
     List<UINode> children = new List.from(items.map((List<UINode> item) {
       double opacity = _opacityFor(i);
       return new PopupMenuItem(key: i++, children: item, opacity: opacity);
     }));
 
+    // border-radius: 2px
+    // inlineStyle: _inlineStyle(),
     return new ShrinkWrapWidth(
-      child: new Material(
-        content: new Container(
-          padding: const EdgeDims.all(8.0),
-          // border-radius: 2px
-          decoration: new BoxDecoration(backgroundColor: Grey[50]),
-          // inlineStyle: _inlineStyle(),
-          child: new BlockContainer(children: children)
-        ),
-        level: level
+      child: new Container(
+        padding: const EdgeDims.all(8.0),
+        decoration: new BoxDecoration(
+          backgroundColor: Grey[50],
+          boxShadow: Shadow[level]),
+        child: new BlockContainer(children: children)
       )
     );
   }
 }