Fix that the graphics helper method will return nil when scale = 0, match the UIKit behavior
Fix that the graphics helper method will return nil when scale = 0, match the UIKit behavior

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