Heavy doses of anxiety, security and elation greeted the imminent arrival of 2018 in Las Vegas. A crowd of 330,000 visitors was expected to fill the Strip and Fremont Street downtown, as a record contingent of law enforcement officers kept the peace. This year’s massive outdoor party unfolded in the shadow of the Oct. 1 mass shooting that left 58 people dead. Several people said they came to celebrate in spite of what happened three months ago Monday.