Fix syntax highlighting of static final property accessed from outside of declaring class

Consider the following:
```groovy
class C {
  static final VALUE = 'value'
  static def foo() {
    VALUE
  }
  static class Inner {
    static def bar() {
      VALUE
    }
  }
}

class Outer {
  def baz = C.VALUE
}
```

Occurrences of `VALUE` in Inner and Outer are highlighted as non-final.  They should be highlighted as final (same as `VALUE` on lines 2 and 4).