You shouldnt bond plastic together with anything other than the exact plastic type of the part you want to bond.
I Imagine the part is abs, it will break again if it is glued as a bumper is a flexible part.
it will be a 2part glue, we use it sometimes on quick easy jobs at work, i think its like bondloc or something to that nature.
If you try to glue it it will be harder to repair second time around!