code: private boolean isGuardedInstanceofReference(Node reference) {
      Node instanceofNode = reference.getParent();
      if (isInstanceofFor(instanceofNode, reference)) {
        Node andNode = instanceofNode.getParent();
        return andNode != null
            && andNode.isAnd()
            && isUndefinedTypeofGuardFor(andNode.getFirstChild(), reference);
      } else {
        return false;
      }
    }
docs: Is the reference node the second {@code Ref} in an expression like {@code 'undefined' != typeof
  Ref && x instanceof Ref}?
  
  <p>It's safe to ignore this kind of reference when moving the definition of {@code Ref}.