Add the test cases for SDImageCacheDecodeFirstFrameOnly on memory cache
Add the test cases for SDImageCacheDecodeFirstFrameOnly on memory cache

awkward/SDWebImage,awkward/SDWebImage,zhang-yawei/SDWebImage,dreampiggy/SDWebImage,dreampiggy/SDWebImage,dreampiggy/SDWebImage,awkward/SDWebImage,rs/SDWebImage,tualatrix/SDWebImage