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

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

 
-class HTMLIFrameElementJs extends HTMLElementJs implements HTMLIFrameElement native "*HTMLIFrameElement" {
+class _HTMLIFrameElementJs extends _HTMLElementJs implements HTMLIFrameElement native "*HTMLIFrameElement" {
 
   String get align() native "return this.align;";
 
   void set align(String value) native "this.align = value;";
 
-  DocumentJs get contentDocument() native "return this.contentDocument;";
+  _DocumentJs get contentDocument() native "return this.contentDocument;";
 
-  DOMWindowJs get contentWindow() native "return this.contentWindow;";
+  _DOMWindowJs get contentWindow() native "return this.contentWindow;";
 
   String get frameBorder() native "return this.frameBorder;";
 
   void set frameBorder(String value) native "this.frameBorder = value;";
 
   String get height() native "return this.height;";
 
   void set height(String value) native "this.height = value;";
 
   String get longDesc() native "return this.longDesc;";
@@ skipping 21 matching lines @@
   void set scrolling(String value) native "this.scrolling = value;";
 
   String get src() native "return this.src;";
 
   void set src(String value) native "this.src = value;";
 
   String get width() native "return this.width;";
 
   void set width(String value) native "this.width = value;";
 
-  SVGDocumentJs getSVGDocument() native;
+  _SVGDocumentJs getSVGDocument() native;
 }