Merge branch 'patch-3' into 'master'

Fix toggler_behavior.js to toggle ajax loaded contents like `diffs` page.

## What does this MR do?

Fix toggle in diffs

## What are the relevant issue numbers?

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/21676, https://gitlab.com/gitlab-org/gitlab-ce/issues/21686.

See merge request !6119

app/assets/javascripts/behaviors/toggler_behavior.js

 (function(w) {
   $(function() {
-    $('.js-toggle-button').on('click', function(e) {
+    $('body').on('click', '.js-toggle-button', function(e) {
       e.preventDefault();
       $(this)
         .find('.fa')