Previously the formatter was using the builtin token table rather that
the one in the current environment. This could lead to round-tripping
failures for user-defined notations.
For an illustrative example, given the following notation
```lean
infixl:65 "+'" => Int.add
notation:65 a:65 "+'-" b:66 => Int.add a (id b)
```
then `5 +' -1` would parse as `Int.add 5 (-1)` and incorrectly pretty
print as `5+'-1`, which in turn would parse as `Int.add 5 (id 1)`. Now
it pretty prints as `5+' -1`.
