Bug 1824064: When cleaning up a11y mutation events, clear the next pointer as...

    acc->SetShowEventTarget(false);

    acc->SetHideEventTarget(false);

    acc->SetReorderEventTarget(false);

    // Our events are in a doubly linked list. We don't need the previous

    // pointers any more, so clear them here to remove reference cycles.

    event->SetPrevEvent(nullptr);

  }

  // 2. Keep the current queue locally, but clear the queue on the instance.

  RefPtr<AccTreeMutationEvent> firstEvent = mFirstMutationEvent;

      }

    }

  }

  // Our events are in a doubly linked list. Clear the pointers to reduce

  // pressure on the cycle collector. Even though clearing the previous pointers

  // removes cycles, this isn't enough. The cycle collector still gets bogged

  // down when there are lots of mutation events if the next pointers aren't

  // cleared. Even without the cycle collector, not clearing the next pointers

  // potentially results in deep recursion because releasing each event releases

  // its next event.

  RefPtr<AccTreeMutationEvent> event = firstEvent;

  while (event) {

    RefPtr<AccTreeMutationEvent> next = event->NextEvent();

    event->SetNextEvent(nullptr);

    event->SetPrevEvent(nullptr);

    event = next;

  }

}

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