Remove _emptyList from fn2.dart

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 512 matching lines @@
     root.callback = callback;
   }
 
   void remove() {
     root.callback = null;
     super.remove();
   }
 
 }
 
-final List<UINode> _emptyList = new List<UINode>();
-
 abstract class MultiChildRenderObjectWrapper extends RenderObjectWrapper {
 
   // In MultiChildRenderObjectWrapper subclasses, slots are RenderObject nodes
   // to use as the "insert before" sibling in ContainerRenderObjectMixin.add() calls
 
   MultiChildRenderObjectWrapper({
     Object key,
     List<UINode> children
-  }) : this.children = children == null ? _emptyList : children,
+  }) : this.children = children == null ? const [] : children,

[Hixie, 2015/06/10 19:39:17]

const <UINode>[]

   super(
     key: key
   ) {
     assert(!_debugHasDuplicateIds());
   }
 
   final List<UINode> children;
 
   void insert(RenderObjectWrapper child, dynamic slot) {
     final root = this.root; // TODO(ianh): Remove this once the analyzer is cleverer
@@ skipping 572 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);
 }