title: React-native: FlatList get refs to scroll
body: <p>I'm currently building an app with react native:</p>
  
  <p>this is my flatlist:</p>
  
  <pre><code>    &lt;FlatList
        ref={"myFlatList"}
        data={data}
        keyExtractor={this._keyExtractor}
        renderItem={this._renderItem}
      /&gt;
  </code></pre>
  
  <p>In this function I want to scroll to a specific index: </p>
  
  <pre><code>  _enableTVEventHandler() {
      this._tvEventHandler = new TVEventHandler();
      this._tvEventHandler.enable(this, function(cmp, evt) {
          this.refs["myFlatList"].scrollToIndex({viewPosition: 0.5, index: 2});
      }.bind(this));
    }
  </code></pre>
  
  <p>But I have an error:
  Cannot read property 'scrollToIndex' of undefined</p>