Fixes renderingMode not applied to GIF images (#24794)

Summary:
Bugs like #24789, we don't apply tintColor to GIF. We fixes it by setting a poster image before add animation.

cc. cpojer .

[iOS] [Fixed] - Fixes renderingMode not applied to GIF images
Pull Request resolved: #24794

Differential Revision: D15316913

Pulled By: cpojer

fbshipit-source-id: 611a07ec17afc962d1eb6b8fc193f118fa623e73

Libraries/Image/RCTImageView.m

@@ -363,10 +363,16 @@ - (void)imageLoaderLoadedImage:(UIImage *)loadedImage error:(NSError *)error for
       self->_pendingImageSource = nil;
     }
 
+    [self->_imageView.layer removeAnimationForKey:@"contents"];
     if (image.reactKeyframeAnimation) {
+      CGImageRef posterImageRef = (__bridge CGImageRef)[image.reactKeyframeAnimation.values firstObject];
+      if (!posterImageRef) {
+        return;
+      }
+      // Apply renderingMode to animated image.
+      self->_imageView.image = [[UIImage imageWithCGImage:posterImageRef] imageWithRenderingMode:self->_renderingMode];
       [self->_imageView.layer addAnimation:image.reactKeyframeAnimation forKey:@"contents"];
     } else {
-      [self->_imageView.layer removeAnimationForKey:@"contents"];
       self.image = image;
     }