Before this commit, when an element with access key has a CSS
position absolute , pressing the key 'ALT' to show the access
key overlay may break the position of the element.
This is due to altering the CSS position of the element which the
overlay is attached to: it becomes `relative`, so that the overlay
takes the whole size of the attached element.
In case of an absolute element, it should not become relative,
otherwise its position on the document may be completely different.
Since the overlay has position `absolute`, if its parent has also
position `absolute`, then keeping both with position `absolute` will
let the overlay take the size of the parent, without changing the
position of the parent.
Task-ID 1885445
Mohammed Shekha
a4bcbecff1