title: FixedDataTable: isMounted is deprecated
body: <p>Using FixedDataTable in my react project and im suprised to see the warning below:</p>
  
  <pre><code>warning.js:36 Warning: FixedDataTable: isMounted is deprecated. Instead, make sure to clean up subscriptions and pending requests in componentWillUnmount to prevent memory leaks.
  </code></pre>
  
  <p>What I've understood is that isMounted is seen as an antipattern <a href="https://facebook.github.io/react/blog/2015/12/16/ismounted-antipattern.html" rel="nofollow noreferrer">Link</a> so im suprised to see it in the actual source code. Am I missing something here?</p>
  
  <pre><code>  _didScrollStop: function _didScrollStop() {
      if (this.isMounted() &amp;&amp; this._isScrolling) {
        this._isScrolling = false;
        this.setState({ redraw: true });
        if (this.props.onScrollEnd) {
          this.props.onScrollEnd(this.state.scrollX, this.state.scrollY);
        }
      }
    }
  </code></pre>