6665445: Backout change to CardTableModRefBS::resize_covered_region()

Summary: Backed out part of cahnge for 6624765 because of nightly testing regressions.  Reviewers below were for 6624765.
Reviewed-by: ysr, apetrusenko

src/share/vm/memory/cardTableModRefBS.cpp

@@ -257,7 +257,7 @@ void CardTableModRefBS::resize_covered_region(MemRegion new_region) {
     }
     assert(index_for(new_region.last()) < (int) _guard_index,
       "The guard card will be overwritten");
-    jbyte* const end = (jbyte*) new_end_for_commit;
+    jbyte* const end = byte_after(new_region.last());
     // do nothing if we resized downward.
     if (entry < end) {
       memset(entry, clean_card, pointer_delta(end, entry, sizeof(jbyte)));