Scripts/Icecrown Citadel: Register Rotface's summons so they can be despawned later

src/server/scripts/Northrend/IcecrownCitadel/boss_rotface.cpp

@@ -178,6 +178,8 @@ class boss_rotface : public CreatureScript
                 if (summon->GetEntry() == NPC_VILE_GAS_STALKER)
                     if (Creature* professor = ObjectAccessor::GetCreature(*me, instance->GetGuidData(DATA_PROFESSOR_PUTRICIDE)))
                         professor->CastSpell(summon, SPELL_VILE_GAS_H, true);
+
+                summons.Summon(summon);
             }
 
             void UpdateAI(uint32 diff) override