reverted:
--- b/core/misc/states.js
+++ a/core/misc/states.js
@@ -509,7 +509,7 @@
     if (e.trigger) {
       $(e.target)
         .prop('disabled', e.value)
+        .closest('.form-item, .form-submit, .form-wrapper').toggleClass('form-disabled', e.value)
-        .closest('.form-item, .form-submit, .form-wrapper').toggleClass('js-form-disabled', e.value)
         .find('select, input, textarea').prop('disabled', e.value);
 
       // Note: WebKit nightlies don't reflect that change correctly.
diff -u b/core/modules/system/templates/form-element.html.twig b/core/modules/system/templates/form-element.html.twig
--- b/core/modules/system/templates/form-element.html.twig
+++ b/core/modules/system/templates/form-element.html.twig
@@ -47,7 +47,7 @@
 #}
 {%
   set classes = [
-    disabled == 'disabled' ? 'js-form-disabled',
+    disabled == 'disabled' ? 'form-disabled',
   ]
 %}
 {%
reverted:
--- b/core/themes/seven/css/components/form.css
+++ a/core/themes/seven/css/components/form.css
@@ -40,20 +40,20 @@
 .form-item label.option input {
   vertical-align: middle;
 }
+.form-disabled label {
-.js-form-disabled label {
   color: #737373;
 }
 
+.form-disabled input.form-text,
+.form-disabled input.form-tel,
+.form-disabled input.form-email,
+.form-disabled input.form-url,
+.form-disabled input.form-search,
+.form-disabled input.form-number,
+.form-disabled input.form-color,
+.form-disabled input.form-file,
+.form-disabled textarea.form-textarea,
+.form-disabled select.form-select {
-.js-form-disabled input.form-text,
-.js-form-disabled input.form-tel,
-.js-form-disabled input.form-email,
-.js-form-disabled input.form-url,
-.js-form-disabled input.form-search,
-.js-form-disabled input.form-number,
-.js-form-disabled input.form-color,
-.js-form-disabled input.form-file,
-.js-form-disabled textarea.form-textarea,
-.js-form-disabled select.form-select {
   border-color: #d4d4d4;
   background-color: hsla(0, 0%, 0%, .08);
   box-shadow: none;