Draggable: Changed logic to only subtract left and top offsets of con…

…tainment if left and top are not already 0. Fixed #4838 - containment: 'document' is incorrect for top and left in draggable

(cherry picked from commit 6e6d0b7)

ui/jquery.ui.draggable.js

@@ -355,8 +355,8 @@ $.widget("ui.draggable", $.ui.mouse, {
 		var o = this.options;
 		if(o.containment == 'parent') o.containment = this.helper[0].parentNode;
 		if(o.containment == 'document' || o.containment == 'window') this.containment = [
-			(o.containment == 'document' ? 0 : $(window).scrollLeft()) - this.offset.relative.left - this.offset.parent.left,
-			(o.containment == 'document' ? 0 : $(window).scrollTop()) - this.offset.relative.top - this.offset.parent.top,
+			o.containment == 'document' ? 0 : $(window).scrollLeft() - this.offset.relative.left - this.offset.parent.left,
+			o.containment == 'document' ? 0 : $(window).scrollTop() - this.offset.relative.top - this.offset.parent.top,
 			(o.containment == 'document' ? 0 : $(window).scrollLeft()) + $(o.containment == 'document' ? document : window).width() - this.helperProportions.width - this.margins.left,
 			(o.containment == 'document' ? 0 : $(window).scrollTop()) + ($(o.containment == 'document' ? document : window).height() || document.body.parentNode.scrollHeight) - this.helperProportions.height - this.margins.top
 		];