Datepicker: Handle clearing the date inside _setDate() as early as possible. Fixes #6684 - Datepicker: setDate() should accept an empty string.
Datepicker: Handle clearing the date inside _setDate() as early as possible. Fixes #6684 - Datepicker: setDate() should accept an empty string.

Thanks RobinHerbots.

GrayYoung/jQuery.UI.Extension,GrayYoung/jQuery.UI.Extension