Improve drawer performance

sky/sdk/lib/widgets/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 'dart:sky' as sky;
+
 import 'package:sky/mojo/asset_bundle.dart';
 import 'package:sky/widgets/basic.dart';
 import 'package:sky/widgets/theme.dart';
 import 'package:sky/widgets/widget.dart';
 
 enum IconThemeColor { white, black }
 
 class IconThemeData {
   const IconThemeData({ this.color });
   final IconThemeColor color;
@@ skipping 24 matching lines @@
 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: '', this.color }) : super(key: key);
+  Icon({
+    String key,
+    this.size,
+    this.type: '',
+    this.color,
+    this.colorFilter
+  }) : super(key: key);
 
   final int size;
   final String type;
   final IconThemeColor color;
+  final sky.ColorFilter colorFilter;
 
   String get colorSuffix {
     IconThemeColor iconThemeColor = color;
     if (iconThemeColor == null) {
       IconThemeData iconThemeData = IconTheme.of(this);
       iconThemeColor = iconThemeData == null ? null : iconThemeData.color;
     }
     if (iconThemeColor == null) {
       ThemeBrightness themeBrightness = Theme.of(this).brightness;
       iconThemeColor = themeBrightness == ThemeBrightness.dark ? IconThemeColor.white : IconThemeColor.black;
@@ skipping 13 matching lines @@
     if (parts.length == 2) {
       category = parts[0];
       subtype = parts[1];
     }
     // TODO(eseidel): This clearly isn't correct.  Not sure what would be.
     // Should we use the ios images on ios?
     String density = 'drawable-xxhdpi';
     return new AssetImage(
       bundle: _iconBundle,
       name: '${category}/${density}/ic_${subtype}_${colorSuffix}_${size}dp.png',
-      size: new Size(size.toDouble(), size.toDouble())
+      size: new Size(size.toDouble(), size.toDouble()),
+      colorFilter: colorFilter
     );
   }
 }