Remove unused mut in servo-util.

src/servo-util/url.rs

@@ -17,7 +17,7 @@ Create a URL object from a string. Does various helpful browsery things like
 */
 #[allow(non_implicitly_copyable_typarams)]
 pub fn make_url(str_url: ~str, current_url: Option<Url>) -> Url {
-    let mut schm = url::get_scheme(str_url);
+    let schm = url::get_scheme(str_url);
     let str_url = if result::is_err(&schm) {
         if current_url.is_none() {
             // Assume we've been given a file path. If it's absolute just return