Function create_a_potential_cors_request 

pub(crate) fn create_a_potential_cors_request(
    webview_id: Option<WebViewId>,
    url: ServoUrl,
    destination: Destination,
    cors_setting: Option<CorsSettings>,
    same_origin_fallback: Option<bool>,
    referrer: Referrer,
) -> RequestBuilder

https://html.spec.whatwg.org/multipage/#create-a-potential-cors-request