The following part of the intestate estate, as to both separate property and the one-half of community property that belongs to the decedent, passes to the surviving spouse:

1. 1. If there is no surviving issue or if there are surviving issue all of whom are issue of the surviving spouse also, the entire intestate estate.
2. 2. If there are surviving issue one or more of whom are not issue of the surviving spouse, one-half of the intestate separate property and no interest in the one-half of the community property that belonged to the decedent.