title: React.createRef is not a function in react-rails
body: <p>A am using react-rails gem in my ruby on rails project. I try to add reference to my DOM element. This is my component:</p>
  
  <pre><code>class NewItem extends React.Component {
    constructor(props) {
      super(props);
      this.name = React.createRef();
    }
    handleClick() {
      var name  = this.name.value;
      console.log(name);
    }
    render() {
      return (
        &lt;div&gt;
          &lt;input ref={this.name} placeholder='Enter the name of the item' /&gt;
          &lt;button onClick={this.handleClick}&gt;Submit&lt;/button&gt;
        &lt;/div&gt;
      );
    }
  };
  </code></pre>
  
  <p>When i try to load the page in browser i have this message in console:
  <code>TypeError: React.createRef is not a function. (In 'React.createRef()', 'React.createRef' is undefined)</code>.</p>