* Yum China, WH Group gain on strong Q1 earnings * China set to report first population drop since 1949 SHANGHAI, April 28 (Reuters) - Hong Kong shares closed higher on Wednesday, with financials and consumer staples leading gains on the back of strong corporate earnings, while investors await cues on policy from politburo meetings due later this week. ** At the close of trade, the Hang Seng index was up 129.80 points or 0.45% at 29,071.34. The Hang Seng China Enterprises index rose 0.28% to 11,014.69. ** The sub-index of the Hang Seng tracking energy shares rose 0.1%, while the IT sector edged up 0.16%, the financial sector ended 0.97% higher and the property sector dipped 0.14%.