By Gerry Shih SAN FRANCISCO (Reuters) – LinkedIn Corp issued a conservative revenue forecast through the end of the year that damped a sizzling run in its stock price, taking the shine off an upbeat performance at the professional social network in the third quarter. The company said it expected between $415 million and $420 million in revenue for the final three months of the year, lower than the $438 million expected by analysts polled by Thomson Reuters I/B/E/S. LinkedIn said fourth-quarter growth will not be as impressive as a year ago when it rolled out new features. …