There’s nothing like a good consumer-price reading to make a Federal Reserve Chairman smile. The price index for May came in flat on Wednesday morning, which made for a confident Chairman Jerome Powell in the afternoon as he explained the latest Federal Open Market Committee decision after its two-day meeting this week. The May CPI came as a relief after three months in row in which inflation had rebounded after last year’s declines. That rebound clearly made an impression on the FOMC, whose...