6848641: CMSCollector::_roots_scanning_options should be initialized Summary: The field is now initialized in the constructor. Reviewed-by: iveresov, jmasa, johnc

Merge

6819065: G1: eliminate high serial card table clearing time Reviewed-by: iveresov, tonyp

6841831: G1: assert(contains_reference(from),"We just added it!") fires Summary: During parallel rset updating we have to make sure that the worker ids of the refinement threads do not intersect with the worker ids that can be claimed by the mutator threads. Reviewed-by: tonyp