Michael Jackson, whose quintessentially American tale of celebrity and excess took him from musical boy wonder to global pop superstar to sad figure haunted by lawsuits, paparazzi and failed plastic surgery, was pronounced dead on Thursday afternoon at U.C.L.A. Medical Center after arriving in a coma, a city official said. Mr. Jackson was 50, having spent 40 of those years in the public eye he loved. The singer was rushed to the hospital, a...