The unsung hero to the Oracle of Omaha's long-term investing outperformance is dividend stocks.In less than three months, billionaire Warren Buffett's illustrious investing career will come to a close. As stated by the Oracle of Omaha at Berkshire Hathaway's (BRK.A 0.34%) (BRK.B 0.42%) annual shareholder meeting in May, he intends to step down from the CEO role at the end of the year and hand the reins over to predetermined successor Greg Abel.The reason Berkshire's shareholders (and investors in general) w ...