A premarital or marital property agreement, whether executed before, on, or after September 1, 2009, that satisfies the requirements of Chapter 4 is effective to waive, release, assign, or partition a claim for economic contribution, reimbursement, or both, under this subchapter to the same extent the agreement would have been effective to waive, release, assign, or partition a claim for economic contribution, reimbursement, or both under the law as it existed immediately before September 1, 2009, unless the agreement provides otherwise.