Fix #10315

This reverts commit db06b25376.

This reverts commit db06b25376.

* fix: update to emoji-mart 2.10.0

* remove useless change

* fix CSS style of emoji picker, improve a11y

* fix missing newline in scss

* fix the title and input fonts

* perf: remove stats.json generation in webpack

* fix code comment

Bumps [webpacker](https://github.com/rails/webpacker) from 3.5.5 to 4.0.2.
- [Release notes](https://github.com/rails/webpacker/releases)
- [Changelog](https://github.com/rails/webpacker/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rails/webpacker/compare/v3.5.5...v4.0.2)

Signed-off-by: dependabot[bot] <support@dependabot.com>
Co-authored-by: Yamagishi Kazutoshi <ykzts@desire.sh>

* Update react-* to v16.7.0

* Upgrade react-hotkeys to v1.1.4

* Update react-intl to v2.7.2

* Update react-select to v2.2.0

* Update react-swipeable-views to v0.13.0

* Upgrade react-textarea-autosize to v7.1.0

* Upgrade redux to v4.0.1

* Upgrade reselect to v4.0.0

* Update raf to v3.4.1

* Update enzyme to v3.8.0

* Update rails-ujs to v5.2.2

* Update axios to v0.18.0

* Update http-link-header to v1.0.2

* Update rellax to v1.7.1

* Update intersection-observer to v0.5.1

* Update stringz to v1.0.0

* Upgrade babel-eslint to v10.0.1

* Update @babel/* to v7.2.x

* Update babel-plugin-react-intl to v3.0.1

* Update babel-plugin-transform-react-remove-prop-types to v0.4.21

* Upgrade dotenv to v6.2.0

* Update express to v4.16.4

* Update webpack to v4.28.3

* Upgrade autoprefixer to v9.4.3

* Update babel-loader to v8.0.4

* Upgrade css-loader to v2.1.0

* Upgrade file-loader to v3.0.1

* Update marky to v1.2.1

* Update mini-css-extract-plugin to v0.5.0

* Update offline-plugin to v5.0.6

* Update style-loader to v0.23.1

* Update eslint-plugin-jsx-a11y to v6.1.2

* yarn upgrade

* fix

* Replace webpack-manifest-plugin to webpack-assets-manifest

* Replace node-zopfli to @gfz/zopfli

* Remove monkey-patch for http-link-header

Webpacker (Ruby wrapper to webpack) uses RAILS_ENV-based environments while
the javascript configuration for webpack re-reads this configuration file using
the NODE_ENV environment variable. This means that when RAILS_ENV=test, running
“assets:precompile” compiled the production packs in “public/packs” while
webpacker expects them in “public/packs-test”. This causes Ruby to recompile
them on-the-fly, possibly leading to race conditions in parallel_tests.

This changes:
- Disables on-the-fly compilation in test environment
- Changes the javascript part to read the correct environment

Webpacker (Ruby wrapper to webpack) uses RAILS_ENV-based environments while
the javascript configuration for webpack re-reads this configuration file using
the NODE_ENV environment variable. This means that when RAILS_ENV=test, running
“assets:precompile” compiled the production packs in “public/packs” while
webpacker expects them in “public/packs-test”. This causes Ruby to recompile
them on-the-fly, possibly leading to race conditions in parallel_tests.

This changes:
- Disables on-the-fly compilation in test environment
- Changes the javascript part to read the correct environment

Still check for S3_CLOUDFRONT_HOST for existing installs.

Bundle most common webpack chunks into a “common” pack,
in a way similar to what upstream does.

Since 872a0d5bd801c998d911f7da582a60d2f714a710, assets URL are absolute and
not relative. Unfortunately, the domain used to build such URLs is the wrong
one: LOCAL_DOMAIN, and not WEB_DOMAIN, where the assets are stored.

* Use PNG images in HTML e-mails

* Make webpack use URLs with host so fonts load inside HTML e-mails

Convert this back to a relative URL in the premailer CSS loader
since local requests are quicker

* Improve responsive design

* Add missing PNG icon

[hash] is not documented.

* Configure webpack to poll for changes in development

Vagrant on Linux/macOS hosts shared files via NFS, which doens't
support inotify-based watching of files. This tweak makes webpack
check for changes every second, and rebuild if necessary. This
removes the need to restart Foreman every time a frontend file
changes. Note that rebuilding is still a relatively lengthy
process.

The polling frequency can be changed to taste.

* Only poll in Vagrant

This tests for the presence of the VAGRANT environment variable to
determine whether or not we're in Vagrant. It is set in .env.vagrant,
which is set up to be included in the Vagrantfile.

* Add support for selecting a theme

* Fix codeclimate issues

* Look up site default style if current user is not available due to e.g. not being logged in

* Remove outdated comment in common.js

* Address requested changes in themes PR

* Fix codeclimate issues

* Explicitly check current_account in application controller and only check theme availability if non-nil

* codeclimate

* explicit precedence with &&

* Fix code style in application_controller according to @nightpool's suggestion, use default style in embedded.html.haml

* codeclimate: indentation + return