RFR(XXS): Assertion fail when printing heap region to trace output

[Zhengyu Gu]

There are a couple of assertion failures when log level set to trace.

1) Print newly created region which has yet added to heap's region set, 
results assertion failure when calling Cset::is_in()

2) Print humongous continue region before it is reclaimed. Verification 
code checks if the region really belongs to a humongous region starting 
with a humongous start region, which has been reclaimed.


Webrev: 
http://cr.openjdk.java.net/~zgu/shenandoah/new_region_assert/webrev.00/

Test:

hotspot_gc_shenandoah + new test: fastdebug + release

Thanks,

-Zhengyu