IE9 and IE10 - Unable to get property 'center' of undefined or null reference

I'm getting this error with the last version of the lib.
Might be because of this line here:

```
var _this = _possibleConstructorReturn(this, Object.getPrototypeOf(GoogleMap).call(this, props));
```

Specifically `Object.getPrototypeOf(GoogleMap).call(this, props)` which I think is not supported by these browsers.

What should we do? Use some sort of polyfill?
