Any land use regulations concerning planned unit developments or planned residential developments adopted by a municipal zoning commission, planning and zoning commission or other applicable zoning authority pursuant to sections 8-13b to 8-13k, inclusive, of the general statutes, revision of 1958, revised to January 1, 1985, shall continue to be valid and any planned unit development or planned residential development proposed in accordance with such regulations which has received approval, whether tentative, preliminary or final, from such commission or authority prior to July 1, 1985, shall continue to be governed by the provisions of such regulations.