Check for naxx map id in slime check.

Author: ratkosrb

src/game/Objects/Player.cpp

@@ -1440,7 +1440,7 @@ void Player::OnMirrorTimerExpirationPulse(MirrorTimer::Type timer)
             if (IsInMagma())
                 EnvironmentalDamage(DAMAGE_LAVA, urand(sWorld.getConfig(CONFIG_UINT32_ENVIRONMENTAL_DAMAGE_MIN), sWorld.getConfig(CONFIG_UINT32_ENVIRONMENTAL_DAMAGE_MAX)));
             // FIXME: Need to skip slime damage in Undercity, maybe someone can find better way to handle environmental damage
-            if (IsInSlime() && m_zoneUpdateId != 1497)
+            if (IsInSlime() && GetMapId() == 533)
                 EnvironmentalDamage(DAMAGE_SLIME, urand(sWorld.getConfig(CONFIG_UINT32_ENVIRONMENTAL_DAMAGE_MIN), sWorld.getConfig(CONFIG_UINT32_ENVIRONMENTAL_DAMAGE_MAX)));
             break;
         case MirrorTimer::FEIGNDEATH: