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

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

 
-class SVGRectJs extends DOMTypeJs implements SVGRect native "*SVGRect" {
+class _SVGRectJs extends _DOMTypeJs implements SVGRect native "*SVGRect" {
 
   num get height() native "return this.height;";
 
   void set height(num value) native "this.height = value;";
 
   num get width() native "return this.width;";
 
   void set width(num value) native "this.width = value;";
 
   num get x() native "return this.x;";
 
   void set x(num value) native "this.x = value;";
 
   num get y() native "return this.y;";
 
   void set y(num value) native "this.y = value;";
 }