dart:json not available on the stand-alone VM

[ThomasLocke]

When trying to do this in a server side daemon:

var config = new Config(filename,
   new ConfigFilesystemLoader(),
   new JsonConfigParser());

return config.readConfig();

I get his error

The built-in library 'dart:json' is not available on the stand-alone VM.
'package:dart_config/parsers/config_parser_json.dart': error: line 4 pos 1: library handler failed
import 'dart:json' as JSON;