A 9-year-old girl with a pacemaker who suffered convulsions on a Chicago bus died after a good Samaritan carried her to a hospital when the bus driver refused to leave his route, said the child’s mother and the man who came to her aid. “The woman was sitting there screaming her baby was having a heart attack, she’s got a pacemaker, and the bus driver was telling her, ‘Get off the . . . bus, lady,’ ” said Ted Garrettson, identified by a hospital spokesman as the man who carried Nicole Hobson into the emergency room. Chicago Transit Authority officials refused to comment, saying they were interviewing the driver.