a822d08bd1
It's now only used in one function. Also, the "should we glue the tokens?" check is only necessary when pushing a `TokenTree::Token`, not when pushing a `TokenTree::Delimited`. As part of this, we now do the "should we glue the tokens?" check immediately, which avoids having look back at the previous token. It also puts all the logic dealing with token gluing in a single place.