What started off as a particularly rough year for Tesla investors is turning into quite the celebration.Following a 36% plunge in the first quarter, the stock's worst period since 2022, Tesla shares have rallied all the way back, reaching an all-time high of $489.48. That tops its prior intraday record of$488.54 reached almost exactly a year ago. The stock got a spark this week after CEO Elon Musk, the world's richest person, said Tesla has been testing driverless vehicles in Austin, Texas with no occupant ...