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

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

 
-class SVGTitleElementJs extends SVGElementJs implements SVGTitleElement native "*SVGTitleElement" {
+class _SVGTitleElementJs extends _SVGElementJs implements SVGTitleElement native "*SVGTitleElement" {
 
   // From SVGLangSpace
 
   String get xmllang() native "return this.xmllang;";
 
   void set xmllang(String value) native "this.xmllang = value;";
 
   String get xmlspace() native "return this.xmlspace;";
 
   void set xmlspace(String value) native "this.xmlspace = value;";
 
   // From SVGStylable
 
-  SVGAnimatedStringJs get className() native "return this.className;";
+  _SVGAnimatedStringJs get className() native "return this.className;";
 
-  CSSStyleDeclarationJs get style() native "return this.style;";
+  _CSSStyleDeclarationJs get style() native "return this.style;";
 
-  CSSValueJs getPresentationAttribute(String name) native;
+  _CSSValueJs getPresentationAttribute(String name) native;
 }