title: How to get multiple static contexts in new CONTEXT API in React v16.6
body: <p>Hi I'm trying to access multiple contexts in a component but I got success with only one context value from provider. there are two providers <code>ListContext</code> and `MappingContext. How can I access contexts like this: </p>
  
  <pre><code>class TableData extends React.Component {
   static contextType = ListContext;
   static contextType = MappingContext;
  
   componentDidMount() {
     const data = this.context // it will have only one context from ListContext
    }
  </code></pre>
  
  <p>I know I can use multiple providers in render() but I want to access the contexts like above. Any help will be appreciated. </p>
  
  <p>Thanks</p>