Issue #1999450 by aaronott: Use Symfony Request for views module.

core/modules/views/lib/Drupal/views/Plugin/views/cache/CachePluginBase.php

@@ -290,9 +290,10 @@ public function generateResultsKey() {
         'langcode' => language(Language::TYPE_INTERFACE)->langcode,
         'base_url' => $GLOBALS['base_url'],
       );
+      $request = \Drupal::request();
       foreach (array('exposed_info', 'page', 'sort', 'order', 'items_per_page', 'offset') as $key) {
-        if (isset($_GET[$key])) {
-          $key_data[$key] = $_GET[$key];
+        if ($request->query->has($key)) {
+          $key_data[$key] = $request->query->get($key);
         }
       }
 

core/modules/views/lib/Drupal/views/Plugin/views/display/DisplayPluginBase.php

@@ -862,7 +862,7 @@ public function getHandlers($type) {
         // If this is during form submission and there are temporary options
         // which can only appear if the view is in the edit cache, use those
         // options instead. This is used for AJAX multi-step stuff.
-        if (isset($_POST['form_id']) && isset($this->view->temporary_options[$type][$id])) {
+        if (\Drupal::request()->request->get('form_id') && isset($this->view->temporary_options[$type][$id])) {
           $info = $this->view->temporary_options[$type][$id];
         }