pub(crate) fn image_fetch_request(
    img_url: ServoUrl,
    origin: ImmutableOrigin,
    referrer: Referrer,
    pipeline_id: PipelineId,
    cors_setting: Option<CorsSettings>,
    referrer_policy: Option<ReferrerPolicy>,
    from_picture_or_srcset: FromPictureOrSrcSet
) -> RequestBuilder