{- -------------------------------------------
  (1) MarkSweep::follow_root() を呼び出すだけ.
      ---------------------------------------- -}

    void MarkSweep::FollowRootClosure::do_oop(oop* p)       { follow_root(p); }
    void MarkSweep::FollowRootClosure::do_oop(narrowOop* p) { follow_root(p); }