Fix folding and syntax highlighting for compact constructor

[eric-milles]

Consider the following:

record Person(String name, Date dob) {
  Person {
    assert name?.size() > 1
    assert dob != null
  }
  Person(Person that) {
    this.name = that.name
  }
}

The compact constructor name is missing highlighting and hover information and the body is missing a collapse control.

[eric-milles]