Factor out `AttrsTarget` flattening code.

This commit does the following.
- Pulls the code out of `AttrTokenStream::to_token_trees` into a new
  function `attrs_and_tokens_to_token_trees`.
- Simplifies `TokenStream::from_ast` by calling the new function. This
  is nicer than the old way, which created a temporary
  `AttrTokenStream` containing a single `AttrsTarget` (which required
  some cloning) just to call `to_token_trees` on it. (It is good to
  remove this use of `AttrsTarget` which isn't related to `cfg_attr`
  expansion.)

0 files changed, 0 insertions, 0 deletions