Works perfectly in FF (FF is my default browser for developing SCW & JACS). SCW is fully cross-browser. If you have a problem with it, ask for help at [email protected] (as per the header of the script).
The relevant bit of your edited script is:
scwDisabledDates[0] = [new Date(scwDateNow.getFullYear()-1, scwDateNow.getMonth(), scwDateNow.getDate()), new Date(scwDateNow) ];
This disables dates from exactly one year ago today through to today.
First, as scwDateNow is a javascript date already, that code should be:
scwDisabledDates[0] = [new Date(scwDateNow.getFullYear()-1, scwDateNow.getMonth(), scwDateNow.getDate()), scwDateNow];
However, to make it disable up to yesterday (instead of up to today) you would need:
scwDisabledDates[0] = [new Date(scwDateNow.getFullYear()-1, scwDateNow.getMonth(), scwDateNow.getDate()), new Date(scwDateNow.getFullYear(), scwDateNow.getMonth(), scwDateNow.getDate()-1)];
...and you are also setting scwDisabledDates[1] as a date range of today through to today... so take that out or today will remain disabled whatever you do to scwDisabledDates[0].