Zero warnings from the analyzer!

sky/sdk/lib/widgets/widget.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:async';
 import 'dart:collection';
 import 'dart:mirrors';
 import 'dart:sky' as sky;
 
 import '../base/hit_test.dart';
@@ skipping 91 matching lines @@
 
   void removeChild(Widget node) {
     node.remove();
   }
 
   void detachRoot();
 
   // Returns the child which should be retained as the child of this node.
   Widget syncChild(Widget node, Widget oldNode, dynamic slot) {
 
-    assert(oldNode is! Component || !oldNode._disqualifiedFromEverAppearingAgain);
+    assert(oldNode is! Component || (oldNode is Component && !oldNode._disqualifiedFromEverAppearingAgain)); // TODO(ianh): Simplify this once the analyzer is cleverer
 
     if (node == oldNode) {
       assert(node == null || node.mounted);
-      assert(node is! RenderObjectWrapper || node._ancestor != null);
+      assert(node is! RenderObjectWrapper || (node is RenderObjectWrapper && node._ancestor != null)); // TODO(ianh): Simplify this once the analyzer is cleverer
       return node; // Nothing to do. Subtrees must be identical.
     }
 
     if (node == null) {
       // the child in this slot has gone away
       assert(oldNode.mounted);
       oldNode.detachRoot();
       removeChild(oldNode);
       assert(!oldNode.mounted);
       return null;
@@ skipping 361 matching lines @@
   RenderObject createNode();
 
   static final Map<RenderObject, RenderObjectWrapper> _nodeMap =
       new HashMap<RenderObject, RenderObjectWrapper>();
   static RenderObjectWrapper _getMounted(RenderObject node) => _nodeMap[node];
 
   RenderObjectWrapper _ancestor;
   void insertChildRoot(RenderObjectWrapper child, dynamic slot);
   void detachChildRoot(RenderObjectWrapper child);
 
-  void _sync(Widget old, dynamic slot) {
+  void _sync(RenderObjectWrapper old, dynamic slot) {
     // TODO(abarth): We should split RenderObjectWrapper into two pieces so that
     //               RenderViewObject doesn't need to inherit all this code it
     //               doesn't need.
     assert(parent != null || this is RenderViewWrapper);
     if (old == null) {
       _root = createNode();
       _ancestor = findAncestor(RenderObjectWrapper);
       if (_ancestor is RenderObjectWrapper)
         _ancestor.insertChildRoot(this, slot);
     } else {
@@ skipping 398 matching lines @@
     if (root.parent == null) {
       // we haven't attached it yet
       assert(_container.child == null);
       _container.child = root;
     }
     assert(root.parent == _container);
   }
 
   Widget build() => builder();
 }