Make dart:dom implementation types private so they don't muddle the docs.

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

Index: client/dom/generated/src/frog/NodeList.dart
diff --git a/client/dom/generated/src/frog/NodeList.dart b/client/dom/generated/src/frog/NodeList.dart
index 1706b3673d26d0a60ef2c47995d6003d79bc4740..fd20963337a9004b9ed0fbdbf2c41c527b1027c7 100644
--- a/client/dom/generated/src/frog/NodeList.dart
+++ b/client/dom/generated/src/frog/NodeList.dart
@@ -1,11 +1,11 @@
 
-class NodeListJs extends DOMTypeJs implements NodeList native "*NodeList" {
+class _NodeListJs extends _DOMTypeJs implements NodeList native "*NodeList" {
 
   int get length() native "return this.length;";
 
-  NodeJs operator[](int index) native "return this[index];";
+  _NodeJs operator[](int index) native "return this[index];";
 
-  void operator[]=(int index, NodeJs value) {
+  void operator[]=(int index, _NodeJs value) {
     throw new UnsupportedOperationException("Cannot assign element of immutable List.");
   }
   // -- start List<Node> mixins.
@@ -76,5 +76,5 @@ class NodeListJs extends DOMTypeJs implements NodeList native "*NodeList" {
 
   // -- end List<Node> mixins.
 
-  NodeJs item(int index) native;
+  _NodeJs item(int index) native;
 }