Remove instances of menu_get_object('user')

It is great to see that there is some effort behind removing menu_get_object().

1. +++ b/core/modules/user/lib/Drupal/user/Plugin/views/argument_default/User.php
   @@ -37,44 +79,24 @@ public function buildOptionsForm(&$form, &$form_state) {
   +    // If there is a user object in the current route.
   +    if ($this->request->attributes->has('user')) {
   +      $user = $this->request->attributes->get('user');
   +      return $user->id();
        }
   

   Maybe we should first check for the interface just in case maybe someone came to the idea that naming something user is a good idea.

2. +++ b/core/modules/user/lib/Drupal/user/Plugin/views/argument_default/User.php
   @@ -37,44 +79,24 @@ public function buildOptionsForm(&$form, &$form_state) {
   +    if (!empty($this->options['user']) && $this->request->attributes->has('node')) {
   +      $node = $this->request->attributes->get('node');
   +      return $node->getAuthorId();
   

   Some with node then.

These two changes should be possible done by a novice.

Thank you for the final change.

Still like before

I don't like that we replaced one magic string with another for getting router arguments, but that's not the fault of this patch. Committed/pushed to 8.x, thanks!