remove unnecessary Key impl

compiler/rustc_query_impl/src/keys.rs

@@ -557,14 +557,3 @@ impl<'tcx> Key for (Ty<'tcx>, ty::ValTree<'tcx>) {
         DUMMY_SP
     }
 }
-
-impl<'tcx> Key for (&'tcx ty::AssocItem, &'tcx ty::AssocItem, ty::TraitRef<'tcx>) {
-    #[inline(always)]
-    fn query_crate_is_local(&self) -> bool {
-        self.0.def_id.krate == LOCAL_CRATE
-    }
-
-    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
-        tcx.def_span(self.0.def_id)
-    }
-}