A progressive Democrat in New York who called Israel’s killing of violent Palestinian protesters on the Gaza border a “massacre” scored a major upset over incumbent Rep. Joe Crowley in a contentious party primary. Alexandria Ocasio-Cortez, 28, defeated Crowley, 56, by a margin of 58-42 percent in Tuesday’s election, toppling a lawmaker who was viewed as the successor to Rep. Nancy Pelosi as speaker of the U.S. House of Representatives. Ocasio-Cortez belongs to the Democratic Socialists of America and is a supporter of Sen. Bernie Sanders, a Vermont Independent who ran as a Democrat in the 2016 presidential primaries. New...