Attach TokenStream to ast::Ty

A `Ty` does not have outer attributes, so we only capture tokens
when parsing a `macro_rules!` matcher

compiler/rustc_ast_lowering/src/lib.rs

@@ -1106,6 +1106,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                                 id: node_id,
                                 kind: TyKind::ImplTrait(impl_trait_node_id, bounds.clone()),
                                 span: constraint.span,
+                                tokens: None,
                             },
                             itctx,
                         );