Sortable: parent containment doesn't work properly when parent element has css max-height property set .Fixes #9460 - Sortable: containment doesn't work properly when scrolling

I have not added any unit test cases for this fix . I do see that Sortable is in general missing `parent containment` and many others test cases . if you guys like the fix - i will try to add unit test cases for it.

Fiddle Fix link - http://jsfiddle.net/2bHSG/12/