diff -u b/core/includes/menu.inc b/core/includes/menu.inc
--- b/core/includes/menu.inc
+++ b/core/includes/menu.inc
@@ -2599,12 +2599,12 @@
 }
 
 /**
- * Finds all links returned from hook_menu_link_defaults().
+ * Gets all default menu link definitions.
  *
  * @return array
  *   An array of default menu links.
  */
-function menu_links_get_defaults() {
+function menu_link_get_defaults() {
   $module_handler = \Drupal::moduleHandler();
   $all_links = $module_handler->invokeAll('menu_link_defaults');
   // Fill in the machine name from the array key.
@@ -2618,19 +2618,20 @@
 /**
  * Builds menu links for the items returned from hook_menu_link_defaults().
  */
-function menu_links_rebuild_defaults() {
+function menu_link_rebuild_defaults() {
   $module_handler = \Drupal::moduleHandler();
   if (!$module_handler->moduleExists('menu_link')) {
     // The Menu link module may not be available during install, so rebuild
     // when possible.
     return;
   }
-  $menu_link_controller = \Drupal::entityManager()
+  /** @var \Drupal\menu_link\MenuLinkStorageControllerInterface $menu_link_storage */
+  $menu_link_storage = \Drupal::entityManager()
     ->getStorageController('menu_link');
   $links = array();
   $children = array();
   $top_links = array();
-  $all_links = menu_links_get_defaults();
+  $all_links = menu_link_get_defaults();
   if ($all_links) {
     foreach ($all_links as $machine_name => $link) {
       // For performance reasons, do a straight query now and convert to a menu
@@ -2649,10 +2650,11 @@
         $link['uuid'] = $existing_item->uuid;
         $link['customized'] = $existing_item->customized;
         $link['updated'] = $existing_item->updated;
-        $menu_link = $menu_link_controller->createFromDefaultLink($link);
+        $menu_link = $menu_link_storage->createFromDefaultLink($link);
 
         // Convert the existing item to a typed object.
-        $existing_item = $menu_link_controller->create(get_object_vars($existing_item));
+        /** @var \Drupal\menu_link\MenuLinkInterface $existing_item */
+        $existing_item = $menu_link_storage->create(get_object_vars($existing_item));
 
         if (!$existing_item->customized) {
           // A change in hook_menu_link_defaults() may move the link to a
@@ -2670,7 +2672,7 @@
           $link['route_name'] = '<front>';
           $link['link_title'] = 'THIS IS A BUG';
         }
-        $menu_link = $menu_link_controller->createFromDefaultLink($link);
+        $menu_link = $menu_link_storage->createFromDefaultLink($link);
       }
       if (!empty($link['parent'])) {
         $children[$link['parent']][$machine_name] = $machine_name;
@@ -2689,14 +2691,14 @@
     }
   }
   foreach ($top_links as $machine_name) {
-    _menu_link_save_recursive($menu_link_controller, $machine_name, $children, $links);
+    _menu_link_save_recursive($menu_link_storage, $machine_name, $children, $links);
   }
   // Handle any children we didn't find starting from top-level links.
   foreach ($children as $orphan_links) {
     foreach ($orphan_links as $machine_name) {
       // Force it to the top level.
       $links[$machine_name]->plid = 0;
-      _menu_link_save_recursive($menu_link_controller, $machine_name, $children, $links);
+      _menu_link_save_recursive($menu_link_storage, $machine_name, $children, $links);
     }
   }
 
diff -u b/core/modules/language/language.module b/core/modules/language/language.module
--- b/core/modules/language/language.module
+++ b/core/modules/language/language.module
@@ -100,7 +100,6 @@
     'description' => 'Configure languages for content and the user interface.',
     'route_name' => 'language.admin_overview',
     'parent' => 'system.admin.config.regional',
-    'weight' => 0,
   );
   // Content language settings.
   $links['language.admin.language.content_settings_page'] = array(
@@ -108,7 +107,7 @@
     'description' => 'Configure language support for content.',
     'route_name' => 'language.content_settings_page',
     'parent' => 'system.admin.config.regional',
-    'weight' => 0,
+    'weight' => 10,
   );
 
   return $links;
diff -u b/core/modules/menu_link/lib/Drupal/menu_link/Entity/MenuLink.php b/core/modules/menu_link/lib/Drupal/menu_link/Entity/MenuLink.php
--- b/core/modules/menu_link/lib/Drupal/menu_link/Entity/MenuLink.php
+++ b/core/modules/menu_link/lib/Drupal/menu_link/Entity/MenuLink.php
@@ -365,9 +365,10 @@
     // 'menu_name' are not stored anywhere else. Since resetting a link happens
     // rarely and this is a one-time operation, retrieving the full set of
     // default menu links does little harm.
-    $all_links = menu_links_get_defaults();
+    $all_links = menu_link_get_defaults();
     $original = $all_links[$this->machine_name];
     $original['machine_name'] = $this->machine_name;
+    /** @var \Drupal\menu_link\MenuLinkStorageControllerInterface $storage_controller */
     $storage_controller = \Drupal::entityManager()->getStorageController($this->entityType);
     $new_link = $storage_controller->createFromDefaultLink($original);
     // Merge existing menu link's ID and 'has_children' property.
diff -u b/core/modules/system/system.module b/core/modules/system/system.module
--- b/core/modules/system/system.module
+++ b/core/modules/system/system.module
@@ -884,7 +884,6 @@
     'link_title' => 'Web services',
     'parent' => 'system.admin.config',
     'route_name' => 'system.admin_config_services',
-    'weight' => 0,
   );
   $items['system.admin.config.services.rss-publishing'] = array(
     'link_title' => 'RSS publishing',