A longtime supporter of Newt Gingrich has donated $5 million to a super PAC backing his presidential bid, providing a major boost to Mr. Gingrich’s ailing campaign in the critical lead-up to Tuesday’s presidential primary in New Hampshire. The donation, reported on Saturday night by The Washington Post, came from Sheldon Adelson, a Las Vegas casino mogul who has long been a generous patron of Mr. GIngrich’s political career. The “super PAC,” Winning Our Future, was formed last month by Becky Burkett, who served until earlier this year as chief development officer for American Solutions, a political action committee that...