Use fields in hidden native DOM classes instead of getters/setters.

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

 
 class _SVGPathSegCurvetoCubicSmoothRelJs extends _SVGPathSegJs implements SVGPathSegCurvetoCubicSmoothRel native "*SVGPathSegCurvetoCubicSmoothRel" {
 
-  num get x() native "return this.x;";
+  num x;
 
-  void set x(num value) native "this.x = value;";
+  num x2;
 
-  num get x2() native "return this.x2;";
+  num y;
 
-  void set x2(num value) native "this.x2 = value;";
-
-  num get y() native "return this.y;";
-
-  void set y(num value) native "this.y = value;";
-
-  num get y2() native "return this.y2;";
-
-  void set y2(num value) native "this.y2 = value;";
+  num y2;
 }