Icons for Menu Item links broke with 8.2 upgrade!

icon.html.twig

{#
/**
 * @file
 * Drupal pass-through template for icon theme hook implementation.
 *
 * @see /themes/THEME/components/icon.twig.
 */
#}

{% embed '@components/icon.twig' %}{% endembed %}

icon.twig

{#
/**
 * @file
 * SVG Icon template
 *
 * Variables:
 * - icon: Name of the icon; SVG should exist as build/img/icons/{icon}.swg
 * - text: Fallback text for screen readers, and when icon is not present.
 * - text_class: Provides a class using boolean text_visible, to add a class
 *   which determines whether fallback text should appear visually or not.
 * - location: Location of text in markup: left (default) or right of icon).
 */
#}
{% set text_class, location =
   text_visible ? 'icon-text' : 'icon-text-fallback',
   location ? location : 'left'
%}
{% if icon %}
  {% if text and location == 'right' %}
    <span class="{{ text_class }}">{{ text }}</span>
  {% endif %}
  <svg class="icon icon-{{ icon }}"><use xlink:href="#icon-{{ icon }}"></use></svg>
  {% if text and location == 'left' %}
    <span class="{{ text_class }}">{{ text }}</span>
  {% endif %}
{% endif %}

search.html.twig

<div class="search">
  <button class="search-toggle">
    <span class="search-toggle-icon search-toggle-icon--expand">
      {% embed '@components/icon.twig' with { icon: 'search-alt', text: 'Toggle Search' } %}{% endembed %}
    </span>
    <span class="search-toggle-icon search-toggle-icon--collapse">
      {% embed '@components/icon.twig' with { icon: 'close-x', text: 'Toggle Search' } %}{% endembed %}
    </span>
  </button>
  {{ form.search }}
  <div class="search-buttons">
    <span class="search-submit-icon">
      {% embed '@components/icon.twig' with { icon: 'search-alt', text: 'Search' }  %}{% endembed %}
    </span>
    {{ form.actions.submit }}
  </div>
  {{ children }}
</div>

theme.theme.php

<?php

use Drupal\Core\Url;

/**
 * Implements hook_theme().
 */
function THEME_theme($existing, $type, $theme, $path) {
  return array(
    // Note: This template (icon.html.twig) is only needed for PHP interactions,
    // e.g. anything that needs to rendered/altered via PHP, such as menu links.
    // The 'icon.twig' implementation can be used directly inside twig templates
    // as opposed to the Drupal hook.
    'icon' => array(
      'template' => 'content/icon',
      'variables' => array(
        'icon' => NULL,
        'text' => NULL,
        'location' => 'left',
        'text_visible' => false,
      ),
    ),
    'search_block_form' => array(
      'template' => 'form/search',
      'render element' => 'form',
    ),
  );
}

/**
 * Implements hook_preprocess_menu().
 */
function THEME_preprocess_menu(&$variables) {
  $menu_name = $variables['menu_name'];
  $menu_items = &$variables['items'];

  /**
   * Supported Menus
   *
   * Defines the menus that should render SVG icons instead of text where
   * available.
   */
  $menus = array(
    'secondary-navigation',
    'footer-social',
  );

  if (in_array($menu_name, $menus)) {
    /**
     * Supported Services
     *
     * - key: String to search in the href.
     * - value: Corresponding icon name to pass to icon template. SVG icon
     *   should exist in `build/img/icons/value.svg`.
     */
    $icons = array(
      'facebook.com' => 'facebook',
      'instagram.com' => 'instagram',
      'twitter.com' => 'twitter',
      'plus.google.com' => 'google-plus',
      'youtube.com' => 'youtube-play',
      'pinterest.com' => 'pinterest',
      'stumbleupon.com' => 'stumbleupon',
      'tumblr.com' => 'tumblr',
      'rss' => 'rss',
      'showfinder' => 'tv',
    );

    foreach ($menu_items as $key => $item) {
      $href = $item['url']->toString();
      $text_visible = ($href == '/showfinder') ? true : false;
      foreach ($icons as $service => $icon) {
        if (stristr($href, $service)) {
          $menu_items[$key]['title'] = array(
            'icon' => array(
              '#theme' => 'icon',
              '#icon' => $icon,
              '#text' => $item['title'],
              '#text_visible' => $text_visible,
            ),
          );
        }
      }
    }
  }
}