Add missing tests for layoutDirection and mirroring

Change-Id: I8eaff4ba2a2a42c5ba01be9a96884ed851c6ee3a
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>
Make sure that layout is invalidated if LayoutMirroring is changed.

The old autotest never tested to see if the layout got rearranged if
_only_ LayoutMirroring got changed. (It was always tested together with
layoutDirection changes).

Change-Id: Ie541ccb101884b8d47770f32b4312bccd2329d47
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>