Visual regression in 12.0: line numbers not lining up in file view

Summary

Line numbers not matching file contents in 12.0

Steps to reproduce

  1. Turn on canary in https://next.gitlab.com
  2. Customize browser font size from standard, e.g. https://gitlab.com/gitlab-org/gitlab-ce/issues/63010#note_179448179
  3. Go to https://gitlab.com/gitlab-org/gitlab-ee/blob/master/ee/lib/gitlab/kubernetes/rollout_status.rb#L35

Example Project

https://gitlab.com/gitlab-org/gitlab-ee/blob/master/ee/lib/gitlab/kubernetes/rollout_status.rb#L35

What is the current bug behavior?

The yellow highlighted line does not line up, as seen on Chrome Version 75.0.3770.80 (Official Build) (64-bit) MacOS

Screen_Shot_2019-06-10_at_4.12.50_PM

What is the expected correct behavior?

Compare to 11.11.2-ee

Screen_Shot_2019-06-10_at_4.13.01_PM

Relevant logs and/or screenshots

(Paste any relevant logs - please use code blocks (```) to format console output, logs, and code as it's tough to read otherwise.)

Output of checks

This bug happens on GitLab.com - 12.0.0-pre 30e31e4a

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

(If you can, link to the line of code that might be responsible for the problem)

Edited by Thong Kuah