A corporation that was not formed as a benefit corporation may become a benefit corporation by amending its articles so that they contain, in addition to matters required by § 13.1-619, a statement that the corporation is a benefit corporation. Any such amendment to the articles of incorporation shall be adopted in accordance with the procedures set forth in § 13.1-707; however, the amendment shall be approved by all shareholders entitled to vote on the amendment, or if no shares have yet been issued, in accordance with § 13.1-709.