Use more deriving(IterBytes) in libsyntax.

src/libsyntax/ast_util.rs

@@ -19,7 +19,6 @@ use visit;
 use std::hashmap::HashMap;
 use std::int;
 use std::option;
-use std::to_bytes;
 use std::cast;
 use std::local_data;
 
@@ -194,14 +193,6 @@ pub fn is_call_expr(e: @expr) -> bool {
     match e.node { expr_call(*) => true, _ => false }
 }
 
-// This makes def_id hashable
-impl to_bytes::IterBytes for def_id {
-    #[inline]
-    fn iter_bytes(&self, lsb0: bool, f: to_bytes::Cb) -> bool {
-        self.crate.iter_bytes(lsb0, f) && self.node.iter_bytes(lsb0, f)
-    }
-}
-
 pub fn block_from_expr(e: @expr) -> blk {
     let blk_ = default_block(~[], option::Some::<@expr>(e), e.id);
     return spanned {node: blk_, span: e.span};