RFR: 8151781: DirtyCardQueue::apply_closure is unused

[Kim Barrett]

Please review this change to remove an unused function, with some
followup cleanup enabled by that removal.

Removed DirtyCardQueue::apply_closure, which is unused.

That allowed apply_closure_to_buffer to be moved from DirtyCardQueue
public static to DirtyCardQueueSet private ordinary member function.
Making it ordinary gives it access to the set's buffer size, so that
value no longer needs to be passed as an argument by the callers.

Also removed the default value for worker_i from
CardTableEntryClosure::do_card_ptr, since all callers pass that
argument.  Default parameter values for virtual functions are a
well-known source of problems.

CR:
https://bugs.openjdk.java.net/browse/JDK-8151781

Webrev:
http://cr.openjdk.java.net/~kbarrett/8151781/webrev.00/

Testing:
JPRT, Aurora default tests.