Removed 'position:relative' for .ui-state-*

I suppose style `position: relative` is too restrictive for .ui-state-* selectors. For example here is description for `.ui-state-default` from http://api.jqueryui.com/:
> Class to be applied to clickable button-like elements. Applies "clickable default" container styles to an element and its child text, links, and icons.

Why button-like elements should always have relative position?