Delta Air Lines, one of the United States’ top carriers, will add two weekly flights connecting Shanghai with Los Angeles due to customer demand at a time of thawing relations between the world’s two biggest economies.The Atlanta-based airline’s weekly direct flights on the cross-Pacific route will rise to five from three in October, Delta said in a statement issued this week. Delta, which aviation intelligence firm OAG ranks as America’s second-largest carrier by number of seats, said that...