Cars line up to pay a toll last month during a festival in Zhengzhou, China. The Chinese economy has been growing, but economists say signs of weakness, including lagging consumer spending, are appearing. (Cui Guangha/Visual China Group/Getty Images) China is redoubling efforts to protect its slowing economy from the effects of a trade war with the United States, providing fresh ammunition for President Trump’s claim that Washington enjoys the upper hand in the deepening commercial conflict. The modest slowdown stands in contrast to the surging U.S. economy, which…