[8u60] RFR of backport for 8068036: assert(is_available(index)) failed in G1 cset

[Thomas Schatzl]

Hi all,

  can I have reviews for the backport of "8068036:
assert(is_available(index)) failed in G1 cset" for 8u60?

It did only apply with minor changes, so I need re-reviews. The problem
is that there are some merge failures with HeapRegion::isHumongous and
friends.

I missed that when backporting 8060025, and so the error occurred in
8u60 testing :(

Full 8u60 changeset:
http://cr.openjdk.java.net/~tschatzl/8068036-8u60/webrev.8u60/

CR:
https://bugs.openjdk.java.net/browse/JDK-8068036
Original change:
http://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/3f138457d7e6

Testing: jprt

Thanks,
  Thomas