Let the propertiesupdate section support dexterity.

When using the properties updater on dexterity objects, it just used to remove the dexterity item from the pipeline, because dexterity objects do not provide Archetype's `IBaseObject`.
Because the item was not yielded when continuing the loop, it was removed from the pipeline and the object was not migrated at all.

This patch fixes the yielding problem when the object does not support properties and enables property updating for dexterity.