title: Image resizeMode='contain' not working in React Native
body: <p>Here's the simplest code possible:</p>
  
  <pre><code>export default class App extends React.Component {
    render() {
      return (
        &lt;View style={styles.container}&gt;
          &lt;Image resizeMode={'contain'} source={imageSource}/&gt;
        &lt;/View&gt;
      )
    }
  }
  
  const styles = StyleSheet.create({
    container: {
      flex: 1,
      backgroundColor: '#fff',
      alignItems: 'center',
      justifyContent: 'center',
    },
  })
  </code></pre>
  
  <p>If the resizeMode is set on 'center', it's working nearly as expected, but when in 'contain', the image does not resize. <a href="https://unsplash.com/photos/-jJQWjfVKec" rel="noreferrer">The image is really huge</a>, but it does not resize... Where am I wrong? :) </p>