CK-Editor: allow details and summary.

Backported from master branch.

Signed-off-by: Thomas Hochstein <thh@inter.net>

docs/NEWS

@@ -1,6 +1,9 @@
 Version 2.3.5-beta1 ()
 ------------------------------------------------------------------------
 
+   * Fix: [CKE] Don't remove <details> and <summary> elements from
+          WYSIWYG editor.
+
    * Fix: Don't delete extend properties from the entryproperties
           plugin when publishing from dashboard (or sending
           delayed trackbacks).

htmlarea/ckeditor_s9y_config.js

@@ -63,9 +63,10 @@ CKEDITOR.editorConfig = function( config ) {
           - Allowed <span> to make life a bit easier!
           - Reset <img[height,width]> Media Library image inserts to avoid ACF OFF removement of height attributes. (Dependency in ckeditor_s9y_plugin.js)
           - Allow <pre[*attributes](*classes)> for custom attributes/classes in code blocks
+          - Allow <details> and <summary>
     */
     // protect
-    config.extraAllowedContent = 'mediainsert[*]{*}(*);gallery[*]{*}(*);media[*]{*}(*);script[*]{*}(*);audio[*]{*}(*);div[*]{*}(*);span[*]{*}(*);img[height,width];pre[*](*);code;figure[*]{*}(*); figcaption[*]{*}(*);';
+    config.extraAllowedContent = 'mediainsert[*]{*}(*);gallery[*]{*}(*);media[*]{*}(*);script[*]{*}(*);audio[*]{*}(*);div[*]{*}(*);span[*]{*}(*);img[height,width];pre[*](*);code;figure[*]{*}(*);figcaption[*]{*}(*);details[*]{*}(*);summary[*]{*}(*);';
     // Do not use auto paragraphs, added to these allowed tags (only!). Please regard that this was marked deprecated by CKE 4.4.5, but is a need for (our use of) extraAllowedContent - check this again by future versions!
     config.autoParagraph = false; // defaults(true)