(a) Except as provided in subdivision (b), the share in a decedent’s estate of a beneficiary who survives the decedent but who dies before distribution shall be distributed under this chapter with the same effect as though the distribution were made to the beneficiary while living.
(b) Subject to Section 21525, distribution may not be made under this chapter if the decedent’s will provides that the beneficiary is entitled to take under the will only if the beneficiary survives the date of distribution or other period stated in the will and the beneficiary fails to survive the date of distribution or other period.