LOS ANGELES — A weekend benefit broadcast featuring recording stars performing live music online from home raised nearly $8 million for two charities serving first responders and Americans facing economic hardship amid the coronavirus crisis, sponsors said on Monday.The Sunday night show, hosted by Elton John from his kitchen, featured Billie Eilish, the Backstreet Boys, Lizzo, Alicia Keys, Mariah Carey, Lady Gaga and Tim McGraw – all appearing by way of smartphones, home cameras or online platforms.The Fox broadcast network carried the hour-long show, dubbed the “iHeart Living Room Concert for America,” live without commercial interruption, drawing 8.7 million television viewers, Fox said.The songs were interspersed with short personal