Starwood Hotels & Resorts Worldwide, Inc continues its aggressive expansion in China with the signing of two new hotels, the Four Points by Sheraton Tianjin, Zhongshan and the Four Points by Sheraton Hangzhou, Binjiang.   Starwood has expanded its portfolio in China significantly in the last two years and now operates 26 hotels in mainland China, Taiwan and Macau, with 27 new hotels under construction, and has become one of the largest international hotel operators in China.   The partnership with Tianjin City Sun Real Estate Development Co., Ltd and Zhejiang Dragon Happy Investment Group Co., Ltd to establish the two new hotels, which will provide the Four Points by Sheraton brand with a major presence in two of the most important travel markets in mainland China, said Miguel Ko, President of Starwood Asia Pacific.