Ensure that sky Nodes are in the document when didMount() is fired. Refactor FixedHeightScrollable …

sky/framework/fn.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 'dart:async';
 import 'dart:collection';
 import 'dart:sky' as sky;
 import 'reflect.dart' as reflect;
@@ skipping 229 matching lines @@
 
   bool _sync(Node old, sky.ParentNode host, sky.Node insertBefore) {
     // print("---Syncing children of $_key");
 
     Element oldElement = old as Element;
 
     if (oldElement == null) {
       // print("...no oldElement, initial render");
 
       _root = sky.document.createElement(_tagName);
+      _parentInsertBefore(host, _root, insertBefore);
       _syncNode();
 
       for (var child in _children) {
         child._sync(null, _root, null);
         assert(child._root is sky.Node);
       }
 
-      _parentInsertBefore(host, _root, insertBefore);
       return false;
     }
 
     _root = oldElement._root;
     oldElement._root = null;
     sky.Element root = (_root as sky.Element);
 
     _syncNode(oldElement);
 
     var startIndex = 0;
@@ skipping 408 matching lines @@
 
       _sync(null, _host, null);
       assert(_root is sky.Node);
 
       sw.stop();
       if (_shouldLogRenderDuration)
         print("Initial render: ${sw.elapsedMicroseconds} microseconds");
     });
   }
 }