MILAN (Reuters) - Italy's economy will shrink by 0.3 percent this year, JPMorgan analysts said, in the gloomiest forecast by a major U.S. bank for the euro zone's third-biggest economy.Official data show Italy fell into its third recession in a decade during the second half of last year, and recent business surveys suggest the economy remains extremely sluggish.The European Commission last week slashed its forecast for Italian GDP growth in 2019 to 0.2 percent, well below the government's 1 percent projection.JPMorgan forecast Italian GDP would contract at an annualised rate of 0.75 percent ...