RFR: [backport] 8057768: Make heap region region type in G1 HeapRegion explicit

[Bengt Rutisson]

Hi all,

I'd like to backport this change:

JDK-8057768: Make heap region region type in G1 HeapRegion explicit

There were some minor merge conflicts, so I need reviews before I push.

Here is the complete webrev for the 8u repo:
http://cr.openjdk.java.net/~brutisso/8057768/webrev.00/

Here is the patch that was pushed to the JDK 9 repo:
http://hg.openjdk.java.net/jdk9/hs-gc/hotspot/rev/13c5569c0fc4

Here is the diff with the merge conflicts that I had to resolve:
http://cr.openjdk.java.net/~brutisso/8057768/webrev.00.diff/

Thanks,
Bengt