Stocks.apk should have icons when run offline

sky/sdk/lib/widgets/icon.dart

Index: sky/sdk/lib/widgets/icon.dart
diff --git a/sky/sdk/lib/widgets/icon.dart b/sky/sdk/lib/widgets/icon.dart
index 3709ca4bc507324068ea1d2a93c92910351584a9..51117235b4fb02791d814cdfd5275147f2ac131e 100644
--- a/sky/sdk/lib/widgets/icon.dart
+++ b/sky/sdk/lib/widgets/icon.dart
@@ -5,8 +5,14 @@
 import '../mojo/asset_bundle.dart';
 import 'basic.dart';
 
-const String _kAssetBase = '/packages/sky/assets/material-design-icons/';
-final AssetBundle _iconBundle = new NetworkAssetBundle(Uri.base.resolve(_kAssetBase));
+AssetBundle _initIconBundle() {
+  if (rootBundle != null)
+    return rootBundle;
+  const String _kAssetBase = '/packages/sky/assets/material-design-icons/';
+  return new NetworkAssetBundle(Uri.base.resolve(_kAssetBase));
+}
+
+final AssetBundle _iconBundle = _initIconBundle();
 
 class Icon extends Component {
   Icon({ String key, this.size, this.type: '' }) : super(key: key);