Upgrade ESLint to version 4.x (#6276)

.codeclimate.yml

.eslintrc.yml

app/javascript/mastodon/components/attachment_list.js

app/javascript/mastodon/components/collapsable.js

app/javascript/mastodon/components/icon_button.js

app/javascript/mastodon/components/status.js

...javascript/mastodon/features/account/components/header.js

app/javascript/mastodon/features/account_gallery/index.js

.../mastodon/features/compose/components/privacy_dropdown.js

...pt/mastodon/features/compose/components/search_results.js

app/javascript/mastodon/features/compose/index.js

app/javascript/mastodon/features/compose/util/url_regex.js

...avascript/mastodon/features/emoji/__tests__/emoji-test.js

app/javascript/mastodon/features/list_editor/index.js

...vascript/mastodon/features/ui/components/column_header.js

app/javascript/mastodon/features/ui/components/modal_root.js

...javascript/mastodon/features/ui/components/upload_area.js

package.json

yarn.lock