RENO — Republican Sen. Dean Heller and Democratic Rep. Shelley Berkley painted each other as enemies of the middle class Thursday in their first debate in one of the nation’s most watched U.S. Senate races.“Nobody has done more to hurt the middle class than my opponent,” said Heller, a former congressman.Berkley, a seven-term congresswoman from Las Vegas, repeated several times that Heller voted “nine times to give tax breaks to oil companies” and “five times to give tax breaks to corporations to ship jobs overseas.”“He talks a good game,” Berkley said. “My opponent is fighting for the big guys, the …