Support CORS attributes for image elements.

components/script/dom/htmlvideoelement.rs

@@ -133,6 +133,7 @@ impl HTMLVideoElement {
         let response = image_cache.find_image_or_metadata(
             poster_url.clone().into(),
             window.origin().immutable().clone(),
+            None,
             UsePlaceholder::No,
             CanRequestImages::Yes,
         );