Use fields in hidden native DOM classes instead of getters/setters.

client/dom/generated/src/frog/NodeIterator.dart

Index: client/dom/generated/src/frog/NodeIterator.dart
diff --git a/client/dom/generated/src/frog/NodeIterator.dart b/client/dom/generated/src/frog/NodeIterator.dart
index 9b2a07373e53ce2b9a205fe1d610ce544e9ada00..25ee0e5c014558549ed93e41ecd6b96203ddecb7 100644
--- a/client/dom/generated/src/frog/NodeIterator.dart
+++ b/client/dom/generated/src/frog/NodeIterator.dart
@@ -1,17 +1,17 @@
 
 class _NodeIteratorJs extends _DOMTypeJs implements NodeIterator native "*NodeIterator" {
 
-  bool get expandEntityReferences() native "return this.expandEntityReferences;";
+  final bool expandEntityReferences;
 
-  _NodeFilterJs get filter() native "return this.filter;";
+  final _NodeFilterJs filter;
 
-  bool get pointerBeforeReferenceNode() native "return this.pointerBeforeReferenceNode;";
+  final bool pointerBeforeReferenceNode;
 
-  _NodeJs get referenceNode() native "return this.referenceNode;";
+  final _NodeJs referenceNode;
 
-  _NodeJs get root() native "return this.root;";
+  final _NodeJs root;
 
-  int get whatToShow() native "return this.whatToShow;";
+  final int whatToShow;
 
   void detach() native;