code: function(serverOffsetThen, d) {
              if (!Splunk.util.isInt(serverOffsetThen)) {
                  return 0;
              }
              // what JS thinks the timezone offset is at the time given by d. This WILL INCLUDE DST
              var clientOffsetThen = d.getTimezoneOffset() * 60;
              // what splunkd told is the actual timezone offset.
              serverOffsetThen     = serverOffsetThen * -60;
  
              return 1000 * (serverOffsetThen - clientOffsetThen);
          }
docs: Given a timezone offset in minutes, and  a JS Date object,
  returns the delta in milliseconds, of the two timezones.
  Note that this will include the offset contributions from DST for both.