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

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

 
-class HTMLLinkElementJs extends HTMLElementJs implements HTMLLinkElement native "*HTMLLinkElement" {
+class _HTMLLinkElementJs extends _HTMLElementJs implements HTMLLinkElement native "*HTMLLinkElement" {
 
   String get charset() native "return this.charset;";
 
   void set charset(String value) native "this.charset = value;";
 
   bool get disabled() native "return this.disabled;";
 
   void set disabled(bool value) native "this.disabled = value;";
 
   String get href() native "return this.href;";
 
   void set href(String value) native "this.href = value;";
 
   String get hreflang() native "return this.hreflang;";
 
   void set hreflang(String value) native "this.hreflang = value;";
 
   String get media() native "return this.media;";
 
   void set media(String value) native "this.media = value;";
 
   String get rel() native "return this.rel;";
 
   void set rel(String value) native "this.rel = value;";
 
   String get rev() native "return this.rev;";
 
   void set rev(String value) native "this.rev = value;";
 
-  StyleSheetJs get sheet() native "return this.sheet;";
+  _StyleSheetJs get sheet() native "return this.sheet;";
 
-  DOMSettableTokenListJs get sizes() native "return this.sizes;";
+  _DOMSettableTokenListJs get sizes() native "return this.sizes;";
 
-  void set sizes(DOMSettableTokenListJs value) native "this.sizes = value;";
+  void set sizes(_DOMSettableTokenListJs value) native "this.sizes = value;";
 
   String get target() native "return this.target;";
 
   void set target(String value) native "this.target = value;";
 
   String get type() native "return this.type;";
 
   void set type(String value) native "this.type = value;";
 }