A federal judge declined to dismiss a lawsuit accusing Chicago Alderman James Gardiner of violating the First Amendment by purportedly blocking critical comments — and sometimes critics themselves — from his official Facebook page.In a written opinion, U.S. District Judge Sharon Johnson Coleman of the Northern District of Illinois did not rule on the merits of the allegations included in the proposed class-action suit filed by six of Gardiner’s constituents.But Coleman held the constituents have …