Most nested block elements are merged together, so while we shouldn't
do real inheritance we need to do it when block elements are combined.
Pick-to: 6.1
Fixes: QTBUG-91236
Change-Id: I9e37b15f705db92c79a620d0d772f25d0ee72b8d
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>