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

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

 
 class _HTMLHRElementJs extends _HTMLElementJs implements HTMLHRElement native "*HTMLHRElement" {
 
-  String get align() native "return this.align;";
+  String align;
 
-  void set align(String value) native "this.align = value;";
+  bool noShade;
 
-  bool get noShade() native "return this.noShade;";
+  String size;
 
-  void set noShade(bool value) native "this.noShade = value;";
-
-  String get size() native "return this.size;";
-
-  void set size(String value) native "this.size = value;";
-
-  String get width() native "return this.width;";
-
-  void set width(String value) native "this.width = value;";
+  String width;
 }