title: What is the prop type for StyleSheet validation
body: <p>I'm writing components for our react-native project</p>
  
  <p>I get this error from prop-types</p>
  
  <p>"Warning: Failed prop type: Invalid prop <code>containerStyle</code> of type <code>number</code> supplied to <code>ImagePicker</code>, expected <code>object</code>."</p>
  
  <p>Simplified example:</p>
  
  <p>common-styles.js
  </p>
  
  <pre><code>    export const defaultStyle = StyleSheet.create({
        container: {
          color: 'red',
          borderWidth: 2
        }
      });
  </code></pre>
  
  <p>image-picker.js
  </p>
  
  <pre><code>    ImagePicker.propTypes = {
        containerStyle: PropTypes.shape(),
      };
  </code></pre>
  
  <p>app.js
  </p>
  
  <pre><code>    &lt;ImagePicker containerStyle={styles.defaultStyle} /&gt;
  </code></pre>
  
  <p>What is the PropType for passing Stylesheet variables?</p>
  
  <p>Thank you</p>