code: void endFinalizerGaps(Env<GenContext> from, Env<GenContext> to) {
          Env<GenContext> last = null;
          while (last != to) {
              endFinalizerGap(from);
              last = from;
              from = from.next;
          }
      }
docs: Mark end of all gaps in catch-all ranges for finalizers of environments
  lying between, and including to two environments.
  @param from    the most deeply nested environment to mark
  @param to      the least deeply nested environment to mark