Mixing style objects and functions messes up specificity resolution

Expected:
```tsx
const Title = styled("h1")(p => ({
  background: "blue"
}));

const Title2 = styled(Title)({
  background: "green"
});
```

Expected:
Title2 is green

Resulted:
Title2 is blue, because it has 2 class names and one of them loses the specificity war.

Repro:
https://codesandbox.io/s/styled-jss-playground-repro-mo3c8
