You have requested a non-existent service "menu_link.tree

In my contrib theme, I render the full main menu tree based on what changed with #2207893: Convert menu tree building to a service..

function gratis_preprocess_page(&$vars, $hook) {
// Build the main menu links tree.
  if (!empty($vars['main_menu'])) {
    // Build links.
    $config = Drupal::config('menu.settings');
    $menu_enabled = Drupal::moduleHandler()->moduleExists('menu');
    // When menu module is not enabled, we need hardcoded default values.
    $main_links_source = $menu_enabled ? $config->get('main_links') : 'main';
    $vars['main_menu'] = \Drupal::service('menu_link.tree')->renderMenu($main_links_source);
    $vars['main_menu']['#attributes']['id'] = 'main-menu-links';
    $vars['main_menu']['#attributes']['class'] = array('links', 'clearfix');
    $vars['main_menu']['#theme_wrappers'] = array('menu_tree__primary');
  }

function gratis_menu_tree__primary(&$vars) {
  return '<ul class="toggle-menu">' . $vars['tree'] . '</ul>';
}

This new method above worked fine as of drupal 8-alpha11 but now with drupal 8.0.0-alpha14, I am getting this error:

Symfony\Component\DependencyInjection\Exception\ServiceNotFoundException: You have requested a non-existent service "menu_link.tree". Did you mean this: "menu.link_tree"? in Symfony\Component\DependencyInjection\Container->get() (line 303 of /Users/danny/Sites/Drupal/d8/drupal8/core/vendor/symfony/dependency-injection/Symfony/Component/DependencyInjection/Container.php).

The part that says:

Did you mean this: "menu.link_tree"?

... is curious and at any rate, I tried that but it did not fix the issue either. My guess is that some other part of the menu system has changed between Alpha 11 and 14 but I just can't figure out what that is.