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

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

 
-class TouchEventJs extends UIEventJs implements TouchEvent native "*TouchEvent" {
+class _TouchEventJs extends _UIEventJs implements TouchEvent native "*TouchEvent" {
 
   bool get altKey() native "return this.altKey;";
 
-  TouchListJs get changedTouches() native "return this.changedTouches;";
+  _TouchListJs get changedTouches() native "return this.changedTouches;";
 
   bool get ctrlKey() native "return this.ctrlKey;";
 
   bool get metaKey() native "return this.metaKey;";
 
   bool get shiftKey() native "return this.shiftKey;";
 
-  TouchListJs get targetTouches() native "return this.targetTouches;";
+  _TouchListJs get targetTouches() native "return this.targetTouches;";
 
-  TouchListJs get touches() native "return this.touches;";
+  _TouchListJs get touches() native "return this.touches;";
 
-  void initTouchEvent(TouchListJs touches, TouchListJs targetTouches, TouchListJs changedTouches, String type, DOMWindowJs view, int screenX, int screenY, int clientX, int clientY, bool ctrlKey, bool altKey, bool shiftKey, bool metaKey) native;
+  void initTouchEvent(_TouchListJs touches, _TouchListJs targetTouches, _TouchListJs changedTouches, String type, _DOMWindowJs view, int screenX, int screenY, int clientX, int clientY, bool ctrlKey, bool altKey, bool shiftKey, bool metaKey) native;
 }