BUG: Styler IndexError when rendering an empty DataFrame
- [x] I have checked that this issue has not already been reported.

- [ ] I have confirmed this bug exists on the latest version of pandas.

- [x] (optional) I have confirmed this bug exists on the master branch of pandas.

---
```python
df = pd.DataFrame()
midx = pd.MultiIndex.from_arrays([["A", "B"], [1, 2]], names=["zero", "one"])
df.style  # OK
df.index=[0,1]
df.style  # OK
df.index=midx
df.style  # IndexError
```

The error here was not the use of MultiIndex but of the index name display row when there are no columns.