[14] RFR (S) 8230853, 8237821: Shenandoah: replace leftover assert(is_in(...)) with rich asserts

[Aleksey Shipilev]

Original change:
  https://bugs.openjdk.java.net/browse/JDK-8230853
  https://hg.openjdk.java.net/jdk/jdk/rev/7e741a3fc650

We need JDK-8237821 change too, which introduced "oop" arguments:
  https://cr.openjdk.java.net/~shade/8230853/webrev.14u.01/

This is already done in sh/jdk11:
  https://hg.openjdk.java.net/shenandoah/jdk11/rev/ec859ee39571

Testing: hotspot_gc_shenandoah {fastdebug,release}, tier{1,2}

-- 
Thanks,
-Aleksey