This regressed in 9a250cc9d6, which allowed static properties to get
overridden by a trait during inheritance. In particular, because of the
change to the loop in zend_update_parent_ce(), it's not guaranteed that
all indirects are after one another.
This means that during persisting the zvals of the static members table,
some static properties may be skipped. In case of the test code, this
means that the array in the trait will keep referring to the old, new
freed, stale value. To solve this, we check the type for IS_INDIRECT,
which is the same as what zend_persist_calc() is already doing anyway.
Since 2543e61aed we can check for IS_INDIRECT to see if it should be
persisted or not.
Closes GH-13794.