Selector date is one day off in certain circumstances

Issue Summary

When using yui_calendar on my test machine (6.2 stable), the date loaded into the text field is one day different from the day selected. I found in the JavaScript [yuicalendar.js]:

YAHOO.drupal.calendar.handleSelect = function(type, args, obj, myCal) {
var dates = args[0];
var date = dates[0];
var year = date[0], month = date[1], day = date[2];

YAHOO.util.Dom.get(myCal.id + '-year').selectedIndex = Math.abs(year - 1969 - YAHOO.util.Dom.get(myCal.id + '-year').length + 1);
YAHOO.util.Dom.get(myCal.id + '-month').selectedIndex = month - 1;
YAHOO.util.Dom.get(myCal.id + '-day').selectedIndex = day - 1;

YAHOO.drupal.calendar.updateDateValue(myCal);
};

When I comment out the subtraction of a day, the day in the text field displays correctly. I'm attaching a patch with that tiny edit.

Honestly, I'm a bit hesitant about this edit, as I'm unclear what the subtraction did in the first place.