title: Context Components in React 16.3 are invalid
body: <p>I'm trying to use the new Context components in React 16.3.1. I'm running a pretty straightforward example:</p>
  
  <pre><code>const TestContext = React.createContext();
  
  export default class Test extends Component {
    render () {
      return (
        &lt;TestContext.Provider value="abc"&gt;
          &lt;TestContext.Consumer&gt;
            {value =&gt; (
              &lt;div&gt;{value}&lt;/div&gt;
            )}
          &lt;/TestContext.Consumer&gt;
        &lt;/TestContext.Provider&gt;
      );
    }
  }
  </code></pre>
  
  <p>However the code won't render, instead producing this error:</p>
  
  <p><code>Uncaught Error: Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: object.</code></p>
  
  <p>It seems that both the Provider and Consumer components aren't valid components and can't be rendered by React.</p>
  
  <p>Am I missing something here?</p>