Issue #3367433 by Spokje: [random test failure] \Drupal\Tests\ckedito…

…r5\FunctionalJavascript\MediaTest::testViewMode random fail

(cherry picked from commit 8053a61b67507de8df86e1072883dec35bb576f8)

modules/ckeditor5/tests/src/FunctionalJavascript/MediaTest.php

@@ -1508,7 +1508,7 @@ public function testViewMode(bool $with_alignment) {
     $drupal_media_element = $editor_dom->getElementsByTagName('drupal-media')
       ->item(0);
     $this->assertFalse($drupal_media_element->hasAttribute('data-view-mode'));
-    $assert_session->elementExists('css', 'article.media--view-mode-view-mode-1');
+    $assert_session->waitForElement('css', 'article.media--view-mode-view-mode-1');
 
     // Test that setting allowed_view_modes back to two items restores the
     // field.
@@ -1551,7 +1551,7 @@ public function testViewMode(bool $with_alignment) {
     $this->assertVisibleBalloon('[aria-label="Drupal Media toolbar"]');
     $this->getBalloonButton('View Mode 1')->click();
     $this->getBalloonButton('View Mode 2 has Numeric ID')->click();
-    $assert_session->elementExists('css', 'article.media--view-mode-_2222');
+    $assert_session->waitForElement('css', 'article.media--view-mode-_2222');
     $this->assertEmpty($assert_session->waitForElementVisible('css', '.drupal-media figcaption'));
 
     // Test that a media with no view modes configured will be