Sen. John Hart delivered his farewell address to the Senate Thursday, just days after revealing he would resign to join a Boston law firm. Hart used the address to thank colleagues and staff and to recall anecdotes from his life growing up in and representing South Boston. Hart highlighted his efforts to develop the South Boston waterfront. "Sixteen years later, it's the hottest piece of real estate in the country, dubbed Boston's innovation district and home today to thousands of new jobs and tens of thousands of new jobs for people around the region a few years down the road," Hart said. Hart joined the House in 1996 and moved to the Senate in 2002. Three Dorchester state representatives, Martin Walsh, Linda Dorcena Forry and Russell Holmes, are mulling runs for Hart's seat, as is former Boston City Councilor Michael Flaherty.