`Nonterminal`-related cleanups In #114647 I am trying to remove `Nonterminal`. It has a number of preliminary cleanups that are worth merging even if #114647 doesn't merge, so let's do them in this PR. r? `@petrochenkov`
None
TokenCursor::break_last_token
Parser
interpolated_or_expr_span
NtOrTt
ParseNtResult