parser: Remove `Deref` impl from `Parser`
Follow up to https://github.com/rust-lang/rust/pull/61541
You have to write `self.token.span` instead of `self.span` in the parser now, which is not nice, but not too bad either, I guess.
Not sure.
Probably still better than people using both and being confused about the definition point of `span`.
r? @oli-obk @estebank
The syntax crate contains those things concerned purely with syntax
– that is, the AST ("abstract syntax tree"), parser, pretty-printer,
lexer, macro expander, and utilities for traversing ASTs.
For more information about how these things work in rustc, see the
rustc guide: