I accidentally removed two lines of code in https://codereview.chromium.org/1172173002 when merging…

sky/sdk/lib/framework/fn2.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.
 
 library fn;
 
 import 'app.dart';
 import 'dart:async';
 import 'dart:collection';
 import 'dart:mirrors';
@@ skipping 868 matching lines @@
   Component.fromArgs(Object key, bool stateful)
       : this(key: key, stateful: stateful);
 
   static Component _currentlyBuilding;
   bool get _isBuilding => _currentlyBuilding == this;
 
   bool _stateful;
   bool _dirty = true;
   bool _disqualifiedFromEverAppearingAgain = false;
 
+  UINode _built;
+  dynamic _slot; // cached slot from the last time we were synced
+
   List<Function> _mountCallbacks;
   List<Function> _unmountCallbacks;
 
   void onDidMount(Function fn) {
     if (_mountCallbacks == null)
       _mountCallbacks = new List<Function>();
 
     _mountCallbacks.add(fn);
   }
 
@@ skipping 211 matching lines @@
   }
 
 }
 
 class Text extends Component {
   Text(this.data) : super(key: '*text*');
   final String data;
   bool get interchangeable => true;
   UINode build() => new Paragraph(text: data);
 }