Performance: ui.draggable uses repeated $( ) for same object

Multiple repeates of the same $() conversion is used throu out the module.

Eexample 1 (Line 275)

var ce = $(o.containment)[0]; if(!ce) return;

var co = $(o.containment).offset();

var over = ($(ce).css("overflow") != 'hidden');

This should probably be faster using a first single $()

var cont = $(o.containment);

var ce = cont[0]; if(!ce) return;

var co = cont.offset();

var over = ($(ce).css("overflow") != 'hidden');

The last row could possibly be replaced with cont if the original o.containment only results in a single element.

Example 2 (line 270)

$(o.containment == 'document' ? document : window).width()

($(o.containment == 'document' ? document : window).height()

Where the same $(o.containmend) is generated repeatedly.