Indonesia’s economy unexpectedly shrank for a second straight quarter as exports and government spending dropped, underscoring the challenge for President Joko Widodo as he seeks to reinvigorate growth. The rupiah fell. Gross domestic product contracted 0.18 percent in the three months ended March 31 from the previous quarter, the statistics bureau said in Jakarta on Tuesday. That compares with the median estimate of a 0.25 percent expansion in a Bloomberg survey of 10 economists.