Mixed compilation: cannot refer to Scala object in Java source

Test.scala
```scala
package p
object O {
  Test.foo()
}
```

Test.java
```scala
package p;
public class Test {
  public static p.O$ foo() { return null; }
}
```

```
$ rm -rf p && scalac11 Test.scala Test.java
Test.java:3: error: not found: type p
  public static p.O$ foo() { return null; }
                ^
one error found
```