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

6484957: G1: parallel concurrent refinement 6826318: G1: remove traversal-based refinement code Summary: Removed traversal-based refinement code as it's no longer used. Made the concurrent refinement (queue-based) parallel. Reviewed-by: tonyp