title: React Virtualized - List skipping over every other item
body: <p>I really don't understand what I'm doing wrong, going by the docs.<br>
  Explanation to the title:<br>
  When I scroll from 1 to 2 (i.e - 1 is now hidden) - everything's fine.<br>
  When I scroll from 2 to 3 (i.e - 1 and 2 are now both hidden) - The List jumps, so it doesn't begin from item 3, it begins with item 4 instead!<br>
  When I scroll all the way down, I have the remainder of all the skipped items, which means there's an empty space in which no item is present .<br>
  here's my code:</p>
  
  <pre><code>
  class MyList extends React.Component {
      rowRenderer = (params: any): JSX.Element =&gt; {
         const color = params.index % 2 ? 'white' : 'blue';
         return (
            &lt;div style={{height: 50, backgroundColor: color}}&gt;
               {this.items[params.index]}
            &lt;/div&gt;
         );
      }
  
      render() {
         &lt;div style={{height: 300}}&gt;
             &lt;List
                 height={300}
                 width={235}
                 rowHeight={50}
                 rowCount={this.items.length}
                 rowRenderer={this.rowRenderer}
             /&gt;
         &lt;/div&gt;
      }
  }
  </code></pre>