Toggle file comments in merge request does not update toggle buttons

Summary

Follow-up from https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/17011:

When clicking the Toggle comments for this file button on a merge request, the individual toggle buttons of the discussions don't get updated and also collapsed discussions don't get expanded.

Steps to reproduce

  • open merge request with discussions
  • click Toggle comments for this file button

What is the current bug behavior?

  • discussion on the left is not expanded
  • toggle button on the right is not updated

new-toggle-file-comments

What is the expected correct behavior?

old-toggle-file-comments