1. Any city of this state framing and adopting a charter for its own government, whether under the provisions of § 19, Article VI of the Constitution of 1945, or under the provisions of Section 16 or Section 20, Article IX of the Constitution of 1875, is hereby defined and declared to be a constitutional charter city.

2. All laws now existing or which may hereafter be enacted relating or making reference to cities under constitutional charter or constitutional charter cities, shall be deemed to and shall apply and be valid only in relation to cities of this state defined and declared in this section to be cities under constitutional charter.