China’s biggest internet companies got that way with at least tacit support from the government. Now two events have raised doubts about where those internet giants stand: the last-minute suspension of a stock offering by billionaire Jack Ma’s Ant Group Co. due to regulatory pressure, and the introduction of a draft antitrust policy designed to rein in the most powerful, including Ant’s major backer, Alibaba Group Holding Ltd., and Tencent Holdings Ltd., operator of the WeChat super-app. The dou