DataCollatorForWholeWordMask error persists after fix
After quick fix #8379
Tried same flow of #8378
**Gives error:**
```
/usr/local/lib/python3.6/dist-packages/transformers/data/data_collator.py in __call__(self, examples)
    321         for e in examples:
    322             ref_tokens = []
--> 323             for id in e["input_ids"].tolist():
    324                 token = self.tokenizer._convert_id_to_token(id)
    325                 ref_tokens.append(token)

AttributeError: 'list' object has no attribute 'tolist'
```

When I tried with _DataCollatorForLanguageModeling_, trainer works as usual.
The problem can be fixed  by changing `e["input_ids"].tolist()` to `e["input_ids"]`  