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

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

 
-class HTMLEmbedElementJs extends HTMLElementJs implements HTMLEmbedElement native "*HTMLEmbedElement" {
+class _HTMLEmbedElementJs extends _HTMLElementJs implements HTMLEmbedElement native "*HTMLEmbedElement" {
 
   String get align() native "return this.align;";
 
   void set align(String value) native "this.align = value;";
 
   String get height() native "return this.height;";
 
   void set height(String value) native "this.height = value;";
 
   String get name() native "return this.name;";
 
   void set name(String value) native "this.name = value;";
 
   String get src() native "return this.src;";
 
   void set src(String value) native "this.src = value;";
 
   String get type() native "return this.type;";
 
   void set type(String value) native "this.type = value;";
 
   String get width() native "return this.width;";
 
   void set width(String value) native "this.width = value;";
 
-  SVGDocumentJs getSVGDocument() native;
+  _SVGDocumentJs getSVGDocument() native;
 }