Completion fails when hiding enclosing type

eg.

```java
public class EnclosingType {
public class EnclosingType {
public String getString() {
ret/* HERE */
}
}
}
```

Completion isn't returned here since the inner `EnclosingType` is marked as an error, since the names overlap. I can understand that completing `EnclosingType./*HERE*/` would be hard/impossible but I think it should be possible to fill in the expected `return`.

Then again, I don't know all the details of how completion is handled. Please let me know if you think it is/isn't feasible.