/sd/source/ui/sidebar/SlideBackground.cxx:176:17: runtime error:
downcast of misaligned address 0x00009cf8cd67 for type 'const
SvxSizeItem', which requires 8 byte alignment

(regression from fba28df7)

Change-Id: I822efe57f35c851b6f63e1e5489ab2448a19963d
Reviewed-on: https://gerrit.libreoffice.org/39753Reviewed-by: Michael Stahl <mstahl@redhat.com>
Tested-by: Michael Stahl <mstahl@redhat.com>