RFR: 8144040: UpdateRSetDeferred in G1EvacFailure will never visit survivor regions

[Erik Helin]

Hi all,

this patch removes an unneeded check from UpdateRSetDeferred which is used in
the case of an evacuation failure. When we start a GC with G1, we
change the type of all survivor regions to eden (see the call to
hr->set_eden_pre_gc() in G1CollectorPolicy::finalize_young_cset_part).
Therefore, if we ever get an evac failure in a region, then that region
must be either young or old. Therefore, we don't need to check for
survivor regions in UpdateRSetDeferred.

Bug:
https://bugs.openjdk.java.net/browse/JDK-8144040

Webrev:
http://cr.openjdk.java.net/~ehelin/8144040/webrev.00/

Testing:
- GC test suite with full verification

Thanks,
Erik