title: Neither setInterval nor setTimeout works react-native ES6
body: <p>I'm trying to get a basic timer going in react-native, but it's not working. I get no errors in the console. It just simply ignores the <code>setInterval</code>. I read the <a href="https://facebook.github.io/react-native/docs/timers.html" rel="noreferrer">TimerMixin</a> issue with ES6 (not supported). So what is the alternative if you want to use just a basic <code>setInterval</code> timer?, as it simply does not work in its simplest form shown here...</p>
  
  <pre><code>import React, { Component } from 'react';
  import { AppRegistry, Text } from 'react-native';
  
  class HelloWorldApp extends Component {
  
  componentDidMount() {
        console.log('COMPONENTDIDMOUNT')
     //this.timer=     &lt;--//This doesn't work either 
       var timer = setInterval(() =&gt; {
        console.log('I do not leak!');
      }, 5000);
    }
  componentWillUnmount() {
      console.log('COMPONENTWILLUNMOUNT')
    clearInterval(timer); 
  }
    render() {
      return (
        &lt;Text&gt;Hello world!&lt;/Text&gt;
      );
    }
  }
  
  AppRegistry.registerComponent('HelloWorldApp', () =&gt; HelloWorldApp);
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/28jsg.png" rel="noreferrer"><img src="https://i.stack.imgur.com/28jsg.png" alt="enter image description here"></a>
  <a href="https://i.stack.imgur.com/E1P4x.png" rel="noreferrer"><img src="https://i.stack.imgur.com/E1P4x.png" alt="enter image description here"></a></p>