(a) Where the slayer holds a reversion or vested remainder in property subject to a life estate in the decedent and the slayer would have obtained the right of present possession upon the death of the decedent, such property shall pass to the estate of the decedent during the period of the life expectancy of the decedent.
(b) Where the slayer holds a reversion or vested remainder in property subject to a life estate in a third person which is measured by the life of the decedent, such property shall remain in the possession of the third person during the period of the life expectancy of the decedent.