The Islamic State is back with another child-soldier video that is even more depraved than the last “Cubs of the Caliphate” release. This time around, the terror state gives us a small child blowing a chained prisoner’s head off in an abandoned amusement park. The most horrifying sequence in the new video shows a much younger boy — ARA News says he is 4 years old — approaching a prisoner chained to the wall of a dusty old ball pit. The little boy is handed a gun, and he proceeds to pump five rounds into the victim while shrieking, “Allahu...