Transitive inlines don't work between files

Minimal example:
```
/* foo.css */

.a {
    color: red;
}

.b {
    @inline .a;
}

/* bar.css */

.c {
    @inline .b from './foo.css';
    font-size: 14px;
}
```

When `.b` is imported, it is imported together with the `@inline`. So .c looks something like

```
.c {
    @inline .a;
    font-size: 14px;
}
```