log(id, noise_threshold, below_threshold, above_threshold, fixed, unconverted) {
    if (id != null) {
      PERF.log_stats_by_id(id, noise_threshold, below_threshold, above_threshold, fixed, unconverted);
    } else {
      for (var id in PERF.stats_by_id) {
        PERF.log_stats_by_id(id, noise_threshold, below_threshold, above_threshold, fixed, unconverted);
      }
    }
  }
Logs stats by id, or all stats recorded when no id present.
@see log_stats_by_id