Overriding getter with member variable causes docs to get lost

Consider the following:

```dart
library foo;

/// Base class docs
class Base {
  /// Great, thorough documentation
  bool get foo => true;
}

/// Subclass docs
class Sub extends Base {
  @override
  final bool foo = false;
}
```

When I look up the dartdocs for `Sub.foo`, I expect to see "Great, thorough documentation".  Yet there are no docs for `Sub.foo`.