editeng: deploy an assert for the default items

Change-Id: Ifc85d682377bb1a3a34e6d49767cbfbe6521c388
n#708518: sd: check that master page matches when setting parent style

In ODF import it happened that the parent style of "outline2" etc.
was always set to the "outline1" style of the first master page in
the document, but it should be the "outline1" style of the same master
page as the "outline2".

(regression from e955433c3574cb602dedba96bc645898f97858bf)

Change-Id: Ie563d5ee5c2040aeb6ca5c8bb25b195e15ea964e