diff --git a/core/modules/ckeditor/src/Tests/CKEditorLoadingTest.php b/core/modules/ckeditor/src/Tests/CKEditorLoadingTest.php
index 7f51130..05b00b9 100644
--- a/core/modules/ckeditor/src/Tests/CKEditorLoadingTest.php
+++ b/core/modules/ckeditor/src/Tests/CKEditorLoadingTest.php
@@ -105,8 +105,8 @@ function testLoading() {
     $this->assertTrue($editor_js_present, 'Text Editor JavaScript is present.');
     $this->assertTrue(count($body) === 1, 'A body field exists.');
     $this->assertTrue(count($format_selector) === 1, 'A single text format selector exists on the page.');
-    $specific_format_selector = $this->xpath('//select[contains(@class, "filter-list") and contains(@class, "editor") and @data-editor-for="edit-body-0-value"]');
-    $this->assertTrue(count($specific_format_selector) === 1, 'A single text format selector exists on the page and has the "editor" class and a "data-editor-for" attribute with the correct value.');
+    $specific_format_selector = $this->xpath('//select[contains(@class, "filter-list") and @data-editor-for="edit-body-0-value"]');
+    $this->assertTrue(count($specific_format_selector) === 1, 'A single text format selector exists on the page and has a "data-editor-for" attribute with the correct value.');
     $this->assertTrue(isset($settings['ajaxPageState']['js']['core/modules/ckeditor/js/ckeditor.js']), 'CKEditor glue JS is present.');
     $this->assertTrue(isset($settings['ajaxPageState']['js']['core/assets/vendor/ckeditor/ckeditor.js']), 'CKEditor lib JS is present.');
 
diff --git a/core/modules/editor/js/editor.js b/core/modules/editor/js/editor.js
index 88f8592..41348cc 100644
--- a/core/modules/editor/js/editor.js
+++ b/core/modules/editor/js/editor.js
@@ -14,10 +14,12 @@
    *   A text format selector DOM element.
    *
    * @return DOM
-   *   The text area DOM element.
+   *   The text area DOM element, if it was found.
    */
   function findFieldForFormatSelector($formatSelector) {
     var field_id = $formatSelector.attr('data-editor-for');
+    // This selector will only find text areas in the top-level document. We do
+    // not support attaching editors on text areas within iframes.
     return $('#' + field_id).get(0);
   }
 
@@ -142,15 +144,18 @@
         return;
       }
 
-      $(context).find('.editor').once('editor', function () {
+      $(context).find('[data-editor-for]').once('editor', function () {
         var $this = $(this);
-        var activeFormatID = $this.val();
-        $this.attr('data-editor-active-text-format', activeFormatID);
         var field = findFieldForFormatSelector($this);
-
+        // Opt-out if no supported text area was found.
         if (!field) {
           return;
         }
+
+        // Store the current active format.
+        var activeFormatID = $this.val();
+        $this.attr('data-editor-active-text-format', activeFormatID);
+
         // Directly attach this text editor, if the text format is enabled.
         if (settings.editor.formats[activeFormatID]) {
           // XSS protection for the current text format/editor is performed on the
@@ -193,10 +198,10 @@
       if (trigger === 'serialize') {
         // Removing the editor-processed class guarantees that the editor will
         // be reattached. Only do this if we're planning to destroy the editor.
-        editors = $(context).find('.editor-processed');
+        editors = $(context).find('.editor-processed[data-editor-for]');
       }
       else {
-        editors = $(context).find('.editor').removeOnce('editor');
+        editors = $(context).find('[data-editor-for]').removeOnce('editor');
       }
 
       editors.each(function () {
diff --git a/core/modules/editor/src/Element.php b/core/modules/editor/src/Element.php
index f0b97bf..868dce0 100644
--- a/core/modules/editor/src/Element.php
+++ b/core/modules/editor/src/Element.php
@@ -67,7 +67,6 @@ function preRenderTextFormat(array $element) {
         '#name' => $element['format']['format']['#name'],
         '#value' => $format_id,
         '#attributes' => array(
-          'class' => array('editor'),
           'data-editor-for' => $field_id,
         ),
       );
diff --git a/core/modules/editor/src/Tests/EditorLoadingTest.php b/core/modules/editor/src/Tests/EditorLoadingTest.php
index 910f6fa..d9c53e2 100644
--- a/core/modules/editor/src/Tests/EditorLoadingTest.php
+++ b/core/modules/editor/src/Tests/EditorLoadingTest.php
@@ -98,8 +98,8 @@ public function testLoading() {
     $this->assertTrue($editor_js_present, 'Text Editor JavaScript is present.');
     $this->assertTrue(count($body) === 1, 'A body field exists.');
     $this->assertTrue(count($format_selector) === 1, 'A single text format selector exists on the page.');
-    $specific_format_selector = $this->xpath('//select[contains(@class, "filter-list") and contains(@class, "editor") and @data-editor-for="edit-body-0-value"]');
-    $this->assertTrue(count($specific_format_selector) === 1, 'A single text format selector exists on the page and has the "editor" class and a "data-editor-for" attribute with the correct value.');
+    $specific_format_selector = $this->xpath('//select[contains(@class, "filter-list") and @data-editor-for="edit-body-0-value"]');
+    $this->assertTrue(count($specific_format_selector) === 1, 'A single text format selector exists on the page and has a "data-editor-for" attribute with the correct value.');
     $this->drupalLogout($this->privileged_user);
 
     // Also associate a text editor with the "Plain Text" text format.
@@ -127,8 +127,8 @@ public function testLoading() {
     $this->assertTrue($editor_js_present, 'Text Editor JavaScript is present.');
     $this->assertTrue(count($body) === 1, 'A body field exists.');
     $this->assertTrue(count($format_selector) === 0, 'No text format selector exists on the page.');
-    $hidden_input = $this->xpath('//input[@type="hidden" and @value="plain_text" and contains(@class, "editor") and @data-editor-for="edit-body-0-value"]');
-    $this->assertTrue(count($hidden_input) === 1, 'A single text format hidden input exists on the page and has the "editor" class and a "data-editor-for" attribute with the correct value.');
+    $hidden_input = $this->xpath('//input[@type="hidden" and @value="plain_text" and @data-editor-for="edit-body-0-value"]');
+    $this->assertTrue(count($hidden_input) === 1, 'A single text format hidden input exists on the page and has a "data-editor-for" attribute with the correct value.');
 
     // Create an "article" node that users the full_html text format, then try
     // to let the untrusted user edit it.