Strong mode fixes for html package

lib/dom.dart

 /// A simple tree API that results from parsing html. Intended to be compatible
 /// with dart:html, but it is missing many types and APIs.
 library dom;
 
 // TODO(jmesserly): lots to do here. Originally I wanted to generate this using
 // our Blink IDL generator, but another idea is to directly use the excellent
 // http://dom.spec.whatwg.org/ and http://html.spec.whatwg.org/ and just
 // implement that.
 
 import 'dart:collection';
@@ skipping 791 matching lines @@
     return result;
   }
 }
 
 /// An indexable collection of a node's descendants in the document tree,
 /// filtered so that only elements are in the collection.
 // TODO(jmesserly): this was copied from dart:html
 // TODO(jmesserly): "implements List<Element>" is a workaround for analyzer bug.
 class FilteredElementList extends IterableBase<Element> with ListMixin<Element>
     implements List<Element> {
-  final Node _node;
   final List<Node> _childNodes;
 
   /// Creates a collection of the elements that descend from a node.
   ///
   /// Example usage:
   ///
   ///     var filteredElements = new FilteredElementList(query("#container"));
   ///     // filteredElements is [a, b, c].
   FilteredElementList(Node node)
-      : _childNodes = node.nodes,
-        _node = node;
+      : _childNodes = node.nodes;
+
 
   // We can't memoize this, since it's possible that children will be messed
   // with externally to this class.
   //
   // TODO(nweiz): we don't always need to create a new list. For example
   // forEach, every, any, ... could directly work on the _childNodes.
   List<Element> get _filtered =>
       new List<Element>.from(_childNodes.where((n) => n is Element));
 
   void forEach(void f(Element element)) {
@@ skipping 167 matching lines @@
 
 class _ConcatTextVisitor extends TreeVisitor {
   final _str = new StringBuffer();
 
   String toString() => _str.toString();
 
   visitText(Text node) {
     _str.write(node.data);
   }
 }