In the past four years, the small Chinese restaurant at 847 Edgell Road in Framingham has changed identities four times as owners came and went: from Harvest Moon to Top Garden, from Top Garden to Yummy Yummy, then to Shanghai City, and then, just two months ago, to Zheng Garden. It’s the type of spot everyone is familiar with, the kind people pass by, wondering if the building is cursed, allowing nothing to flourish within its walls.