To woo these iconic companies — among them P&G, Estée Lauder, and Macy's — Alibaba is pitching itself as a shortcut to the world's most populous market. Alibaba is helping foreign companies with marketing, data analytics, and shipping. And more recently it has sweetened the pot with a newer service, Tmall Global, that lets U.S. brands sidestep many of the taxes, regulatory hurdles, and logistics hassles that trip up foreign companies in China.