TRENTON — Gov. Chris Christie hosted a frontrunner for the Republican presidential nomination on Monday night, sitting down with Mitt Romney for dinner at the governor's mansion. Nearly two dozen people, including some of Christie's top political advisers and party leaders, gathered for the meeting with the former Massachusetts governor at Drumthwacket, according to three sources. The sources described the dinner as an informal discussion without any specific talk of endorsements in New Jersey's Republican presidential primary, which is still a year away. Romney has been laying the groundwork for a second presidential campaign, although he has not yet formally...