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

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

 
-class SVGPathSegArcRelJs extends SVGPathSegJs implements SVGPathSegArcRel native "*SVGPathSegArcRel" {
+class _SVGPathSegArcRelJs extends _SVGPathSegJs implements SVGPathSegArcRel native "*SVGPathSegArcRel" {
 
   num get angle() native "return this.angle;";
 
   void set angle(num value) native "this.angle = value;";
 
   bool get largeArcFlag() native "return this.largeArcFlag;";
 
   void set largeArcFlag(bool value) native "this.largeArcFlag = value;";
 
   num get r1() native "return this.r1;";
 
   void set r1(num value) native "this.r1 = value;";
 
   num get r2() native "return this.r2;";
 
   void set r2(num value) native "this.r2 = value;";
 
   bool get sweepFlag() native "return this.sweepFlag;";
 
   void set sweepFlag(bool value) native "this.sweepFlag = 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;";
 }