message: Ignore GIF's background color
  It seems that Firefox and Chrome ignore it and just set the background
  color to transparent.
diff: @@ -109,7 +109,6 @@ struct GifFrameIterator<R: Read> {
  width: u32,
  height: u32,
  - background_color: Rgba<u8>,
  non_disposed_frame: ImageBuffer<Rgba<u8>, Vec<u8>>,
  }
  @@ -121,40 +120,15 @@ impl<R: Read> GifFrameIterator<R> {
  // TODO: Avoid this cast
  let (width, height) = (width as u32, height as u32);
  - // set the background color to be either the bg_color defined in the gif
  - // or a transparent pixel.
  - let background_color_option = decoder.reader.bg_color();
  - let mut background_color = vec![0; 4];
  - let background_pixel = {
  - let global_palette = decoder.reader.global_palette();
  - match background_color_option {
  - Some(index) => {
  - // find the color by looking in the global palette
  - match global_palette {
  - // take the color from the palette that is at the index defined
  - // by background_color_option
  - Some(slice) => {
  - background_color.clone_from_slice(&slice[index..(index + 4)]);
  - Rgba::from_slice(&background_color)
  - }
  - // if there is no global palette, assign the background color to be
  - // transparent
  - None => Rgba::from_slice(&[0, 0, 0, 0]),
  - }
  - }
  - // return a transparent background color
  - None => Rgba::from_slice(&[0, 0, 0, 0]),
  - }
  - };
  + // intentionally ignore the background color for web compatibility
  - // the background image is the first non disposed frame
  - let non_disposed_frame = ImageBuffer::from_pixel(width, height, *background_pixel);
  + // create the first non disposed frame
  + let non_disposed_frame = ImageBuffer::from_pixel(width, height, Rgba([0, 0, 0, 0]));
  GifFrameIterator {
  reader: decoder.reader,
  width,
  height,
  - background_color: *background_pixel,
  non_disposed_frame,
  }
  }
  @@ -249,7 +223,7 @@ impl<R: Read> Iterator for GifFrameIterator<R> {
  // (background shows through transparent pixels in the next frame)
  for y in top..top + f_height {
  for x in left..left + f_width {
  - self.non_disposed_frame.put_pixel(x, y, self.background_color);
  + self.non_disposed_frame.put_pixel(x, y, Rgba([0, 0, 0, 0]));
  }
  }
  }
  