Linking to the first note in a thread does not highlight it anymore

Summary

When linking to a note it's usually highlighted to show which note specifically is being linked to. This does not work anymore for the first note of a thread or lone notes without threads.

Steps to reproduce

Click this and it will not be highlighted !123936 (comment 1449246384)

Click this and it will be highlighted !123936 (comment 1451515151)

Example Project

What is the current bug behavior?

Clicking a direct link to a note does not highlight it

What is the expected correct behavior?

Clicking a direct link to a note should highlight it

Relevant logs and/or screenshots

Output of checks

This bug happens on GitLab.com

Results of GitLab environment info

Expand for output related to GitLab environment info

(For installations with omnibus-gitlab package run and paste the output of:
`sudo gitlab-rake gitlab:env:info`)

(For installations from source run and paste the output of:
`sudo -u git -H bundle exec rake gitlab:env:info RAILS_ENV=production`)

Results of GitLab application Check

Expand for output related to the GitLab application check

(For installations with omnibus-gitlab package run and paste the output of:
sudo gitlab-rake gitlab:check SANITIZE=true)
(For installations from source run and paste the output of:
sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production SANITIZE=true)
(we will only investigate if the tests are passing)

Possible fixes