[2.2.x] Fixed #30299 -- Removed jQuery dependency from getCookie() in CSRF docs.

Backport of 8e675e2bd8 from master

docs/ref/csrf.txt

@@ -84,13 +84,12 @@ Acquiring the token is straightforward:
 
 .. code-block:: javascript
 
-    // using jQuery
     function getCookie(name) {
         var cookieValue = null;
         if (document.cookie && document.cookie !== '') {
             var cookies = document.cookie.split(';');
             for (var i = 0; i < cookies.length; i++) {
-                var cookie = jQuery.trim(cookies[i]);
+                var cookie = cookies[i].trim();
                 // Does this cookie string begin with the name we want?
                 if (cookie.substring(0, name.length + 1) === (name + '=')) {
                     cookieValue = decodeURIComponent(cookie.substring(name.length + 1));