6662086: 6u4+, 7b11+: CMS never clears referents when -XX:+ParallelRefProcEnabled Summary: Construct the relevant CMSIsAliveClosure used by CMS during parallel reference processing with the correct span. It had incorrectly been constructed with an empty span, a regression introduced in 6417901. Reviewed-by: jcoomes

1cc8dd79fd1cd13d36b385196271a29632c67c3b jdk7-b24
bf2517e15f0c0f950e5b3143c4ca11e2df73dcc1 jdk7-b25