Inconsistent real-time checkbox

Summary

If there are checkboxes in a comment block, other checkboxes do not work as intended.

Steps to reproduce

1. Make a new issue or a merge request.

2. Input the following.

<!--
- [ ] a
- [ ] b
- [ ] c
-->

- [ ] d
- [ ] e
- [ ] f
- [ ] g
- [ ] h
- [ ] i

3. Summit the issue.

4. If the d, e, f checkboxes are checked, the selections will be canceled when the page is updated.

• In an edit mode, the a, b, c checkboxes in annotation range are checked instead of d, e, f checkboxes.
• Comments on document change history have been added as shown below.
  • 

5. If the g, h, i checkboxes are checked, the selections will be canceled when the page is updated. But the d, e, f checkboxes will be checked.

Example Project

devinjeon/checkbox_bug_report#1

This is the same issue document as the example of Steps to reproduce

What is the current bug behavior?

This is the problem that the checkbox in a comment block is activated in the document. (The checkboxes in a comment block are not visible in the page, but they are activated.)

The checkboxes in a comment block cause the problem that the indices of all checkboxes are shifted.

This problem causes inconvenience in using the template.

What is the expected correct behavior?

The checkboxes in a comment block must be treated as a comment.

Relevant logs and/or screenshots

I made a GIF image to show my Steps to reproduce

Results of GitLab environment info

Expand for output related to GitLab environment info

System information
System:         Ubuntu 14.04
Proxy:          no
Current User:   git
Using RVM:      no
Ruby Version:   2.3.7p456
Gem Version:    2.6.14
Bundler Version:1.13.7
Rake Version:   12.3.1
Redis Version:  3.2.11
Git Version:    2.16.3
Sidekiq Version:5.0.5
Go Version:     go1.2.1 linux/amd64
GitLab information
Version:        10.8.1-ee
Revision:       921025f
Directory:      /opt/gitlab/embedded/service/gitlab-rails
DB Adapter:     postgresql
DB Version:     9.6.6
URL:            http://...
HTTP Clone URL: http://.../some-group/some-project.git
SSH Clone URL:  git@...:some-group/some-project.git
Elasticsearch:  yes
Geo:            no
Using LDAP:     no
Using Omniauth: no
GitLab Shell
Version:        7.1.2
Repository storage paths:

• default: /var/opt/gitlab/git-data/repositories Hooks: /opt/gitlab/embedded/service/gitlab-shell/hooks Git: /opt/gitlab/embedded/bin/git

But, It occurs not only in EE Edition but also in CE Edition include gitlab.com.

Results of GitLab application Check

Too long to paste. But everything is okay in my environment.

Possible fixes

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