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

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

 
-class TouchListJs extends DOMTypeJs implements TouchList native "*TouchList" {
+class _TouchListJs extends _DOMTypeJs implements TouchList native "*TouchList" {
 
   int get length() native "return this.length;";
 
-  TouchJs operator[](int index) native "return this[index];";
+  _TouchJs operator[](int index) native "return this[index];";
 
-  void operator[]=(int index, TouchJs value) {
+  void operator[]=(int index, _TouchJs value) {
     throw new UnsupportedOperationException("Cannot assign element of immutable List.");
   }
   // -- start List<Touch> mixins.
   // Touch is the element type.
 
   // From Iterable<Touch>:
 
   Iterator<Touch> iterator() {
     // Note: NodeLists are not fixed size. And most probably length shouldn't
     // be cached in both iterator _and_ forEach method. For now caching it
@@ skipping 50 matching lines @@
     throw new UnsupportedOperationException("Cannot removeRange on immutable List.");
   }
   void insertRange(int start, int length, [Touch initialValue]) {
     throw new UnsupportedOperationException("Cannot insertRange on immutable List.");
   }
   List<Touch> getRange(int start, int length) =>
       _Lists.getRange(this, start, length, <Touch>[]);
 
   // -- end List<Touch> mixins.
 
-  TouchJs item(int index) native;
+  _TouchJs item(int index) native;
 }