Remove unused selectors::Element::each_class

components/selectors/tree.rs

@@ -74,10 +74,4 @@ pub trait Element: Sized {
     /// Note: this can be false even if `.parent_element()` is `None`
     /// if the parent node is a `DocumentFragment`.
     fn is_root(&self) -> bool;
-
-    // Ordinarily I wouldn't use callbacks like this, but the alternative is
-    // really messy, since there is a `JSRef` and a `RefCell` involved. Maybe
-    // in the future when we have associated types and/or a more convenient
-    // JS GC story... --pcwalton
-    fn each_class<F>(&self, callback: F) where F: FnMut(&<Self::Impl as SelectorImpl>::ClassName);
 }