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

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

 
 class _FileExceptionJs extends _DOMTypeJs implements FileException native "*FileException" {
 
   static final int ABORT_ERR = 3;
 
   static final int ENCODING_ERR = 5;
 
   static final int INVALID_MODIFICATION_ERR = 9;
 
   static final int INVALID_STATE_ERR = 7;
 
   static final int NOT_FOUND_ERR = 1;
 
   static final int NOT_READABLE_ERR = 4;
 
   static final int NO_MODIFICATION_ALLOWED_ERR = 6;
 
   static final int PATH_EXISTS_ERR = 12;
 
   static final int QUOTA_EXCEEDED_ERR = 10;
 
   static final int SECURITY_ERR = 2;
 
   static final int SYNTAX_ERR = 8;
 
   static final int TYPE_MISMATCH_ERR = 11;
 
-  int get code() native "return this.code;";
+  final int code;
 
-  String get message() native "return this.message;";
+  final String message;
 
-  String get name() native "return this.name;";
+  final String name;
 
   String toString() native;
 }