8138740: Start initial mark right after mixed GC if needed Summary: Instead of issuing a single young-only GC after the end of all mixed GCs, if needed immediately start an initial mark in that young-only GC. Reviewed-by: drwhite, mgerdin

8139874: After G1 Full GC, the next GC is always a young-only GC Summary: Allow initiation of an initial mark after Full GC Reviewed-by: ehelin