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

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

 
 class _HTMLMetaElementJs extends _HTMLElementJs implements HTMLMetaElement native "*HTMLMetaElement" {
 
-  String get content() native "return this.content;";
+  String content;
 
-  void set content(String value) native "this.content = value;";
+  String httpEquiv;
 
-  String get httpEquiv() native "return this.httpEquiv;";
+  String name;
 
-  void set httpEquiv(String value) native "this.httpEquiv = value;";
-
-  String get name() native "return this.name;";
-
-  void set name(String value) native "this.name = value;";
-
-  String get scheme() native "return this.scheme;";
-
-  void set scheme(String value) native "this.scheme = value;";
+  String scheme;
 }