Make package: work like Dart expects in preparation for a Sky SDK

sky/framework/components/icon.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';
 
-const String kAssetBase = '/sky/assets/material-design-icons';
+// TODO(eseidel): This should use package:.
+const String kAssetBase = '/packages/sky/assets/material-design-icons';
 
 class Icon extends Component {
   List<Style> styles;
   int size;
   String type;
 
   Icon({
     String key,
     this.styles,
     this.size,
@@ skipping 10 matching lines @@
     }
 
     return new Image(
       styles: styles,
       width: size,
       height: size,
       src: '${kAssetBase}/${category}/2x_web/ic_${subtype}_${size}dp.png'
     );
   }
 }