Rollup merge of #35917 - jseyfried:remove_attr_ext_traits, r=nrc

syntax: Remove traits `AttrMetaMethods`, `AttributeMethods`, and `AttrNestedMetaItemMethods`

src/libsyntax/ext/expand.rs

@@ -13,7 +13,6 @@ use ast::{MacStmtStyle, Stmt, StmtKind, ItemKind};
 use ast;
 use ext::hygiene::Mark;
 use attr::{self, HasAttrs};
-use attr::AttrMetaMethods;
 use codemap::{dummy_spanned, ExpnInfo, NameAndSpan, MacroBang, MacroAttribute};
 use syntax_pos::{self, Span, ExpnId};
 use config::StripUnconfigured;