Merge branch '3.4' into 4.2

* 3.4:
  fix javascript typo

Author: javiereguiluz

reference/forms/types/collection.rst

@@ -151,7 +151,7 @@ you need is this JavaScript code:
         jQuery('.add-another-collection-widget').click(function (e) {
             var list = jQuery(jQuery(this).attr('data-list-selector'));
             // Try to find the counter of the list or use the length of the list
-            var counter = list.data('widget-counter') | list.children().length;
+            var counter = list.data('widget-counter') || list.children().length;
 
             // grab the prototype template
             var newWidget = list.attr('data-prototype');