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

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

 
 class _HTMLParamElementJs extends _HTMLElementJs implements HTMLParamElement native "*HTMLParamElement" {
 
-  String get name() native "return this.name;";
+  String name;
 
-  void set name(String value) native "this.name = value;";
+  String type;
 
-  String get type() native "return this.type;";
+  String value;
 
-  void set type(String value) native "this.type = value;";
-
-  String get value() native "return this.value;";
-
-  void set value(String value) native "this.value = value;";
-
-  String get valueType() native "return this.valueType;";
-
-  void set valueType(String value) native "this.valueType = value;";
+  String valueType;
 }