title: syntax 'nullishCoalescingOperator' isn't currently enabled
body: <p>when I tried to build my app on ios-simulator it says :</p>
  
  <p>bundling failed: SyntaxError: /Users/MyName/MyApp/node_modules/react-native/node_modules/react-native/Libraries/Components/Switch/Switch.js: Support for the experimental syntax <code>nullishCoalescingOperator</code> isn't currently enabled (167:52):</p>
  
  <pre><code> 165 |         {...props}
    166 |         {...platformProps}
  &gt; 167 |         accessibilityRole={props.accessibilityRole ?? 'button'}
        |                                                    ^
    168 |         onChange={this._handleChange}
    169 |         onResponderTerminationRequest={returnsFalse}
    170 |         onStartShouldSetResponder={returnsTrue}
  </code></pre>
  
  <p><code>Add @babel/plugin-proposal-nullish-coalescing-operator (https://git.io/vb4Se) to the 'plugins' section of your Babel config to enable transformation.</code></p>
  
  <p>I did what it says, but it just didn't help...
  Any help will be appreciated.</p>