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

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

 
-class HTMLMarqueeElementJs extends HTMLElementJs implements HTMLMarqueeElement native "*HTMLMarqueeElement" {
+class _HTMLMarqueeElementJs extends _HTMLElementJs implements HTMLMarqueeElement native "*HTMLMarqueeElement" {
 
   String get behavior() native "return this.behavior;";
 
   void set behavior(String value) native "this.behavior = value;";
 
   String get bgColor() native "return this.bgColor;";
 
   void set bgColor(String value) native "this.bgColor = value;";
 
   String get direction() native "return this.direction;";
@@ skipping 29 matching lines @@
   void set vspace(int value) native "this.vspace = value;";
 
   String get width() native "return this.width;";
 
   void set width(String value) native "this.width = value;";
 
   void start() native;
 
   void stop() native;
 }