Fix migrations testing support RSpec hooks order

Closes #33583

See merge request !12120

Replace PhantomJS with headless Chrome in frontend test suite

See merge request !12036

Center dropdown for pipeline's  mini graph

Closes #27586

See merge request !12087

Refactor atom builder by using a layout

See merge request !12114

Documentation bugfix of invalid JSON payload example of Create a commit with multiple files and actions

See merge request !12117

Documentation bugfix of invalid JSON payload example of Create a commit with multiple files and actions

Fix filename method of GitlabUploader to return always real filename

Closes #33524

See merge request !12113

Ignore CVE-2017-5029 in Nokogiri

Closes #33597

See merge request !12109

Let PhantomJS load local images

See merge request !12003

Set artifact working directory to be in the destination store to prevent unnecessary I/O

Closes #33274

See merge request !11905

Add an optional performance bar to view performance metrics for the current page

Closes #29010

See merge request !11439

Prevent Description Change Notes When Toggling Tasks

Closes #32834

See merge request !12057

This change fix a memory leak due to a Webkit bug:
https://github.com/ariya/phantomjs/issues/12903

Also:

- Whitelist only localhost and 127.0.0.1 in Capybara + JS specs
- Blacklist all requests to media such as images, videos, PDFs, CSVs etc.
- Log all the requests made.
Signed-off-by: Rémy Coutable <remy@rymai.me>

Add the ability to perform background migrations

See merge request !11854

Attempts to run RSpec tests twice (1 retry)

See merge request !12066

Ignore commit status name validation on importing

Closes #33490

See merge request !12039

Use :request_store hooks on specs

See merge request !12058

Update gitlab-workhorse to v2.1.1

See merge request !12049

Fix a few translation for zh_TW

See merge request !12043

Generate patch with git diff instead of git format-patch

Closes #33525

See merge request !12060

Use gitaly 0.11.2

See merge request !12092

Doc: Add the need to upgrade to Go 1.8.3 in the 9.1->9.2 documentation as the upgrade fails with Go 1.5 (installed with Gitlab 8.1)

See merge request !12078

Doc: Add the need to upgrade to Go 1.8.3 in the 9.1->9.2 documentation as the upgrade fails with Go 1.5 (installed with Gitlab 8.1)

Fix FIDO U2F for Opera browser (based on !10118)

See merge request !12082

Background migrations can be used to perform long running data
migrations without these blocking a deployment procedure.

See MR https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/11854 for
more information.