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

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

 
-class HTMLFrameElementJs extends HTMLElementJs implements HTMLFrameElement native "*HTMLFrameElement" {
+class _HTMLFrameElementJs extends _HTMLElementJs implements HTMLFrameElement native "*HTMLFrameElement" {
 
-  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;";
 
   int get height() native "return this.height;";
 
   String get location() native "return this.location;";
 
   void set location(String value) native "this.location = value;";
@@ skipping 21 matching lines @@
   String get scrolling() native "return this.scrolling;";
 
   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;";
 
   int get width() native "return this.width;";
 
-  SVGDocumentJs getSVGDocument() native;
+  _SVGDocumentJs getSVGDocument() native;
 }