RFR: 8166898: G1SATBCardTableLoggingModRefBS::invalidate() incorrect with whole_heap == true

[Leonid Mesnik]

Hi

Could you please review following fix. It is implemented as suggested in 
the bug comments.

webrev http://cr.openjdk.java.net/~lmesnik/8166898/webrev.00/ 
<http://cr.openjdk.java.net/%7Elmesnik/8166898/webrev.00/>

bug: https://bugs.openjdk.java.net/browse/JDK-8166898

Testing: JPRT, RBT tier2-4 on linux-x64-debug and tier2 on all platforms 
(in progress).

Leonid