Remove Origin::unicode_serialization

Fixes #20701

components/url/origin.rs

@@ -89,11 +89,6 @@ impl ImmutableOrigin {
     pub fn ascii_serialization(&self) -> String {
         self.clone().into_url_origin().ascii_serialization()
     }
-
-    /// <https://html.spec.whatwg.org/multipage/#unicode-serialisation-of-an-origin>
-    pub fn unicode_serialization(&self) -> String {
-        self.clone().into_url_origin().unicode_serialization()
-    }
 }
 
 /// Opaque identifier for URLs that have file or other schemes