Since .panel-heading is a bit different from bootstrap, using .panel-title for h3 looks different.

So with this .panel-title will look good again inheriting custom properties our app sets for .panel-heading

Since there’s only one dropdown of this type we don’t need a class to create this dropdown masively.

We should stop passing events as a parameter since we cannot call the method programatically without faking or creating an event even when that event is not entirely required.

Since there are only one dropdown of each type there are no need to create a class to initialize multiple elements with the same CSS class name.

Also updates protect branch list

Added tests to dateTime utility getDayName method

## What does this MR do?

It was missing tests so i've created some tests to check the correct day name is returned

See merge request !5324

Added changelog item for issuable form dropdowns

## What does this MR do?

Adds CHANGELOG item about the new dropdowns in the issuable form

See merge request !5266

Fixed enter submitting form in dropdown

## What does this MR do?

When searching for a branch in the ref switcher & then pressing enter it would submit the form without anything. This instead doesn't submit the form without anything being selected in the dropdown.

Also improved the UX by making it submit with `Turoblinks` as currently no loading bar is shown so the user has no idea if anything is happening.

## What are the relevant issue numbers?

Closes #19549 

See merge request !5111

Update timeago to shorter representation

## What does this MR do?
Shortens representation of `Finished at` block in pipelines & builds

## What are the relevant issue numbers?
Closes #19752    
Part of https://gitlab.com/gitlab-org/gitlab-ce/issues/18920

## Screenshots (if relevant)
![Screen_Shot_2016-07-14_at_8.54.44_AM](/uploads/85000549c49165d4481422eac5eb0ca9/Screen_Shot_2016-07-14_at_8.54.44_AM.png)

See merge request !5225

Bump gitlab_git to lazy load compare commits

See merge request !5667

Guide about what requires downtime

## What does this MR do?

This MR adds a guide describing various SQL operations and whether they need downtime or not.

## Are there points in the code the reviewer needs to double check?

Spalling and styling of the text mostly.

## Why was this MR needed?

Developers aren't always aware of the impact of certain operations and the documentation of MySQL and PostgreSQL can be quite confusing at times.

## Screenshots (if relevant)

![screenshot](/uploads/d8afd4bd3755d26e4786dfafecfa9368/screenshot.png)

<img src="https://emoji.slack-edge.com/T02592416/trollface/8c0ac4ae98.png" width="60" />

## Does this MR meet the acceptance criteria?

- [x] ~~[CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added~~
- [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- Tests
  - [ ] All builds are passing
- [ ] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5672

Ignore URLs starting with // in Markdown links

## What does this MR do?

Render `[foo](//bar/baz)` as `<a href="//bar/baz">foo</a>`.

## Why was this MR needed?

`[foo](//bar/baz)` currently renders as `<a href="//bar/gitlab-org/gitlab-ce/master/baz">foo</a>`

## What are the relevant issue numbers?

fixes #7032

See merge request !5677

Add issue description to txt/plain emails

## What does this MR do?
Adds issue description to new_issue mail when in text/plain content-type

## Are there points in the code the reviewer needs to double check?

## Why was this MR needed?
Because clients that are rendering emails in text mode can see issue description 

## What are the relevant issue numbers?
#1821 

## Screenshots (if relevant)

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- Tests
  - [ ] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5663

Add unfold links for Side-by-Side view

## What does this MR do?

Add unfold links for Side-by-Side view and refactor some diff related code

## What are the relevant issue numbers?

Closes #3877 

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [x] API support added
- Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5415

Upgrade newrelic_rpm from 3.14.1.311 to 3.16.0.318.

## What does this MR do?

While we intend to remove newrelic in the future, it'll probably not happen until 9.0 due to. In the meantime, I'd like to update the gem so it won't block Rails 5.

Changelog: https://github.com/newrelic/rpm/blob/master/CHANGELOG

## Why was this MR needed?

Rails 5 compatibility.

Relevant issues: #14286, #12860 

See merge request !5553

Move abilities by subject class to a dedicated method

## What does this MR do?

Twin of gitlab-org/gitlab-ee!622.

It moves the `case` that returns abilities depending on the subject class to a dedicated method.

This should avoid lame conflicts when CE to EE since the EE version assign the result of the `case` to a variable.

## What are the relevant issue numbers?

Closes #20621.

See merge request !5668

Add a data migration to fix some missing timestamps in the members table (again)

## What does this MR do?

Repeats an earlier migration to fix historic bad data in the members table (missing created_at and updated_at fields)

## Are there points in the code the reviewer needs to double check?

I'm expecting the WHERE clauses to be fast enough, and to return few enough rows, that the migration doesn't need to use batches, but I'm not too familiar with the size of these tables in the wild, so perhaps that's a poor assumption. 

## Why was this MR needed?

8.10 introduced a dependency on the  `members.created_at` field in the project and namespace member view. If bad data is present, viewing the list of members now results in an NoMethodError and a 500 response from GitLab. Although the previous migration should have fixed all bad rows, we have evidence that it didn't in at least one case, despite the migration claiming to have run in the past.

## What are the relevant issue numbers?

#20568 

## Screenshots (if relevant)

## Does this MR meet the acceptance criteria?

- [ ] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- Tests
  - [ ] Added for this feature/bug
  - [ ] All builds are passing
- [ ] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

Closes #20568

See merge request !5670

Set consistency in list text height css

Fix line height of list row. Now its 42px everywhere. Before this merge request certain row height varied from 40 to 45px. Sometimes even inside one list. 

cc @jschatz1 @connorshea 

See merge request !5666

Migrate protected branch access levels to match constants in `Gitlab::Access`

Closes #20606 

Context: https://gitlab.com/gitlab-org/gitlab-ce/issues/20606#note_13561628

See merge request !5658

Fix `#down` for two protected branches-related migrations.

- The migrations called `add_column_with_default` with a `null` option, which the Rails `add_column` method accepts. This fails because `add_column_with_default` expects an `allow_null` option instead.

- The migrations have been fixed to use `allow_null`.

See merge request !5660

This guide describes various commonly used operations and the impact
they have on the availability of a GitLab instance.