quick_info_date

specifies the date of the pop-up edit form

start	Date	the date when a task is scheduled to begin
end	Date	the date when a task is scheduled to be completed
task	Task	the task object

gantt.templates.quick_info_date = function(start, end, task){
       return gantt.templates.task_time(start, end, task);
};

Details

This template is defined in the Quick Info extension, so you need to activate the quick_info plugin.