Silence a bunch of annoying bogus dartanalyzer warnings.

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 318 matching lines @@
 
   OneChildRenderObjectWrapper({ this.child, Object key }) : super(key: key);
 
   void syncRenderObject(RenderObjectWrapper old) {
     super.syncRenderObject(old);
     UINode oldChild = old == null ? null : (old as OneChildRenderObjectWrapper).child;
     syncChild(child, oldChild, null);
   }
 
   void insert(RenderObjectWrapper child, dynamic slot) {
+    final root = this.root; // TODO(ianh): Remove this once the analyzer is cleverer
     assert(slot == null);
+    assert(root is RenderObjectWithChildMixin);
     root.child = child.root;
+    assert(root == this.root); // TODO(ianh): Remove this once the analyzer is cleverer
   }
 
   void removeChild(UINode node) {
+    final root = this.root; // TODO(ianh): Remove this once the analyzer is cleverer
+    assert(root is RenderObjectWithChildMixin);
     root.child = null;
     super.removeChild(node);
+    assert(root == this.root); // TODO(ianh): Remove this once the analyzer is cleverer
   }
 
   void _remove() {
     if (child != null)
       removeChild(child);
     super._remove();
   }
 }
 
 class Clip extends OneChildRenderObjectWrapper {
@@ skipping 119 matching lines @@
     Object key,
     List<UINode> children
   }) : this.children = children == null ? _emptyList : children,
   super(
     key: key
   ) {
     assert(!_debugHasDuplicateIds());
   }
 
   void insert(RenderObjectWrapper child, dynamic slot) {
+    final root = this.root; // TODO(ianh): Remove this once the analyzer is cleverer
     assert(slot == null || slot is RenderObject);
     assert(root is ContainerRenderObjectMixin);
     root.add(child.root, before: slot);
+    assert(root == this.root); // TODO(ianh): Remove this once the analyzer is cleverer
   }
 
   void removeChild(UINode node) {
+    final root = this.root; // TODO(ianh): Remove this once the analyzer is cleverer
     assert(root is ContainerRenderObjectMixin);
     root.remove(node.root);
     super.removeChild(node);
+    assert(root == this.root); // TODO(ianh): Remove this once the analyzer is cleverer
   }
 
   void _remove() {
     assert(children != null);
     for (var child in children) {
       assert(child != null);
       removeChild(child);
     }
     super._remove();
   }
@@ skipping 10 matching lines @@
                 of another node, they must have unique keys.
                 Duplicate: "${child._key}"''';
       }
     }
     return false;
   }
 
   void syncRenderObject(MultiChildRenderObjectWrapper old) {
     super.syncRenderObject(old);
 
+    final root = this.root; // TODO(ianh): Remove this once the analyzer is cleverer
     if (root is! ContainerRenderObjectMixin)
       return;
 
     var startIndex = 0;
     var endIndex = children.length;
 
     var oldChildren = old == null ? [] : old.children;
     var oldStartIndex = 0;
     var oldEndIndex = oldChildren.length;
 
@@ skipping 56 matching lines @@
       ensureOldIdMap();
       oldNode = oldNodeIdMap[currentNode._key];
       if (oldNode == null)
         return false;
 
       oldNodeIdMap[currentNode._key] = null; // mark it reordered
       assert(root is ContainerRenderObjectMixin);
       assert(old.root is ContainerRenderObjectMixin);
       assert(oldNode.root != null);
 
-      old.root.remove(oldNode.root);
+      (old.root as ContainerRenderObjectMixin).remove(oldNode.root); // TODO(ianh): Remove cast once the analyzer is cleverer
       root.add(oldNode.root, before: nextSibling);
 
       return true;
     }
 
     // Scan forwards, this time we may re-order;
     nextSibling = root.firstChild;
     while (startIndex < endIndex && oldStartIndex < oldEndIndex) {
       currentNode = children[startIndex];
       oldNode = oldChildren[oldStartIndex];
@@ skipping 21 matching lines @@
       startIndex++;
     }
 
     // Removals
     currentNode = null;
     while (oldStartIndex < oldEndIndex) {
       oldNode = oldChildren[oldStartIndex];
       removeChild(oldNode);
       advanceOldStartIndex();
     }
+
+    assert(root == this.root); // TODO(ianh): Remove this once the analyzer is cleverer
   }
 }
 
 class BlockContainer extends MultiChildRenderObjectWrapper {
   RenderBlock root;
   RenderBlock createNode() => new RenderBlock();
 
   BlockContainer({ Object key, List<UINode> children })
     : super(key: key, children: children);
 }
@@ skipping 365 matching lines @@
     assert(root.parent is RenderView);
   }
 }
 
 class Text extends Component {
   Text(this.data) : super(key: '*text*');
   final String data;
   bool get interchangeable => true;
   UINode build() => new Paragraph(text: data);
 }