Weird behavior using chart.toggle() and legend labels.

To reproduce the issue I've issued the `chart.toggle()` method. All datasets are hidden. This is right.
But now, I manually clicked any dataset in the legend. It's toggled. This is right again, but if I issue the `chart.toggle()` in this state, the legend doesn't get modified.

I've been able to solve this using this:

``` javascript
chart.toggle();
chart.legend.hide();
chart.legend.show();
```