title: Value of type 'StorageMetadata' has no member 'downloadURL'
body: <p>I just updated Firebase Storage to 5.0.0 and it looks like <code>metadata.downloadURL()</code> is not recognized anymore. (<code>Value of type 'StorageMetadata' has no member 'downloadURL'</code>)</p>
  
  <p>Though after looking in the documentation it should still be available : </p>
  
  <p><a href="https://firebase.google.com/docs/reference/swift/firebasestorage/api/reference/Classes/StorageMetadata#/c:objc(cs)FIRStorageMetadata(im)downloadURL" rel="noreferrer">https://firebase.google.com/docs/reference/swift/firebasestorage/api/reference/Classes/StorageMetadata#/c:objc(cs)FIRStorageMetadata(im)downloadURL</a></p>
  
  <p>The project was cleaned &amp; rebuilt already. </p>
  
  <p>Am I missing something ? </p>