Reformat with rustfmt 1.4.36-nightly (7de6968 2021-02-07)

components/script/dom/treewalker.rs

@@ -467,7 +467,7 @@ impl<'a> Iterator for &'a TreeWalker {
             // which cannot produce an Err result.
             {
                 unreachable!()
-            },
+            }
         }
     }
 }