Parser: semantic highlighting is wrong (?)

[magnus-madsen]

/// Polymorphically extends the record `r` with an `age` label.
/// Preserves (retains) all other labels polymorphically.
def withAge(r: {| a}, v: Int32): {age = Int32 | a} =
    { +age = v | r }

/// Polymorphically restricts (removes) the `age` label from `r`.
/// Preserves (retains) all other labels polymorphically.
def withoutAge(r: {age = Int32 | a}): {| a} = {-age | r}

/// Construct several records and extend them with an age.
def main(): Unit \ IO =
    let r1 = withAge({fstName = "Julius", lstName = "Caesar"}, 55);
    let r2 = withAge({monument = "Flavian Amphitheatre"}, 2019 - 80);
    let r3 = withAge({country = "United States"}, 2019 - 1776);
    (r1.age + r2.age + r3.age) |> println

[magnus-madsen]

@herluf-ba I have upgraded this to high priority because it could indicate the some source locations are wrong which could make other compiler errors appear in wrong places.