LanguageService.getReferencesAtPosition does not find all references

The following code used to find the reference for variable `z` in line2 correctly pre-1.0, but now fails to find the reference within the function `func`:

```
    export class ABCD {
        constructor(private x: number, public y: number, private z: number) {
        }

        func() {
            return this.z;
        }
    }
```
