Oil prices are off to their best-ever start to a year as fears of a supply glut cool, part of a 2019 recovery in risky investments from stocks to commodities. U.S. crude-oil futures have rebounded about 25% in the first two months of the year, according to Dow Jones Market Data, the best January-February performance in figures going back to 1984. Oil is also heading for its best two-month stretch generally since 2016—when prices recovered in April and May of that year after dipping below $27 a barrel. …