Don't override the isDecoded = YES for non-CGContext drawn CGImage

Author: dreampiggy

SDWebImageWebPCoder/Classes/SDImageWebPCoder.m

@@ -347,7 +347,6 @@ - (UIImage *)decodedImageWithData:(NSData *)data options:(nullable SDImageCoderO
         UIImage *firstFrameImage = [[UIImage alloc] initWithCGImage:imageRef scale:scale orientation:kCGImagePropertyOrientationUp];
 #endif
         firstFrameImage.sd_imageFormat = SDImageFormatWebP;
-        firstFrameImage.sd_isDecoded = YES; // We handle byte alignment and alloc bitmap buffer
         CGImageRelease(imageRef);
         WebPDemuxReleaseIterator(&iter);
         WebPDemuxDelete(demuxer);
@@ -1339,7 +1338,6 @@ - (UIImage *)safeAnimatedImageFrameAtIndex:(NSUInteger)index {
     image = [[UIImage alloc] initWithCGImage:imageRef scale:_scale orientation:kCGImagePropertyOrientationUp];
 #endif
     image.sd_imageFormat = SDImageFormatWebP;
-    image.sd_isDecoded = YES; // We handle byte alignment and alloc bitmap buffer
     CGImageRelease(imageRef);
 
     WebPDemuxReleaseIterator(&iter);