No longer just a manufacturer for the world, China has become the largest market for many consumer, luxury and durable goods, as an expanding middle class flexes its spending power. Now, its newfound restraint is pounding the world’s No. 2 economy and rippling across the globe, crimping oil producers, electronics makers, travel services and a slew of other sectors. Apple Inc. is the latest company to sound the warning, on Wednesday attributing a sharp falloff in iPhone revenue to China’s rapidly decelerating economy. Ford Motor Co. and General Motors Co. have reported significant sales drops for China in a monthslong slump that has hit foreign and domestic auto makers alike. E-commerce titans, which thrived on robust consumer spending, are hitting speed bumps, with Alibaba Group Holding Ltd. cutting its revenue forecast and Inc. reporting a fall in active customer accounts. “If people are not buying new apartments or […]