interdiff impossible; taking evasive action
reverted:
--- b/core/modules/media_library/js/media_library.view.es6.js
+++ a/core/modules/media_library/js/media_library.view.es6.js
@@ -44,25 +44,24 @@
         'media-library-select-all',
       );
       if ($view.length && $view.find('.media-library-item').length) {
+        const $checkbox = $(
+          '<input type="checkbox" class="form-checkbox" />',
+        ).on('click', ({ currentTarget }) => {
+          // Toggle all checkboxes.
+          const $checkboxes = $(currentTarget)
+            .closest('.media-library-view')
+            .find('.media-library-item input[type="checkbox"]');
+          $checkboxes
+            .prop('checked', $(currentTarget).prop('checked'))
+            .trigger('change');
+          // Announce the selection.
+          const announcement = $(currentTarget).prop('checked')
+            ? Drupal.t('Zero items selected')
+            : Drupal.t('All @count items selected', {
+                '@count': $checkboxes.length,
+              });
+          Drupal.announce(announcement);
+        });
-        const $checkbox = $(Drupal.theme('checkbox')).on(
-          'click',
-          ({ currentTarget }) => {
-            // Toggle all checkboxes.
-            const $checkboxes = $(currentTarget)
-              .closest('.media-library-view')
-              .find('.media-library-item input[type="checkbox"]');
-            $checkboxes
-              .prop('checked', $(currentTarget).prop('checked'))
-              .trigger('change');
-            // Announce the selection.
-            const announcement = $(currentTarget).prop('checked')
-              ? Drupal.t('Zero items selected')
-              : Drupal.t('All @count items selected', {
-                  '@count': $checkboxes.length,
-                });
-            Drupal.announce(announcement);
-          },
-        );
         const $label = $(
           '<label class="media-library-select-all"></label>',
         ).text(Drupal.t('Select all media'));
unchanged:
--- a/core/modules/media_library/js/media_library.view.es6.js
+++ b/core/modules/media_library/js/media_library.view.es6.js
@@ -16,24 +16,25 @@
         'media-library-select-all',
       );
       if ($view.length && $view.find('.js-media-library-item').length) {
-        const $checkbox = $(
-          '<input type="checkbox" class="form-checkbox" />',
-        ).on('click', ({ currentTarget }) => {
-          // Toggle all checkboxes.
-          const $checkboxes = $(currentTarget)
-            .closest('.media-library-view')
-            .find('.js-media-library-item input[type="checkbox"]');
-          $checkboxes
-            .prop('checked', $(currentTarget).prop('checked'))
-            .trigger('change');
-          // Announce the selection.
-          const announcement = $(currentTarget).prop('checked')
-            ? Drupal.t('Zero items selected')
-            : Drupal.t('All @count items selected', {
-                '@count': $checkboxes.length,
-              });
-          Drupal.announce(announcement);
-        });
+        const $checkbox = $(Drupal.theme('checkbox')).on(
+          'click',
+          ({ currentTarget }) => {
+            // Toggle all checkboxes.
+            const $checkboxes = $(currentTarget)
+              .closest('.media-library-view')
+              .find('.js-media-library-item input[type="checkbox"]');
+            $checkboxes
+              .prop('checked', $(currentTarget).prop('checked'))
+              .trigger('change');
+            // Announce the selection.
+            const announcement = $(currentTarget).prop('checked')
+              ? Drupal.t('Zero items selected')
+              : Drupal.t('All @count items selected', {
+                  '@count': $checkboxes.length,
+                });
+            Drupal.announce(announcement);
+          },
+        );
         const $label = $(
           '<label class="media-library-select-all"></label>',
         ).text(Drupal.t('Select all media'));