code: function _startTimeout(o, t) {
          _timeout[o.id] = w.setTimeout(function() { _ioCancel(o, 'timeout'); }, t);
      }
docs: @description Starts timeout count if the configuration object
  has a defined timeout property.
  
  @method _startTimeout
  @private
  @static
  @param {object} o - Transaction object generated by _create().
  @param {object} t - Timeout in milliseconds.
  @return void