* add postcss-preset-env, remove autoprefixer

* limit to stage 4

* Add new overrides option

* Add file to package.json

* Create our own loader

* Remove overrides

* We have to use a real babel option

* Add comments

Closes https://github.com/facebook/create-react-app/issues/5081

Husky had an overhaul of the API, see https://github.com/typicode/husky
Therefore the usage advice here has been adjusted.

follwing -> following

* Add user defined proxy via middleware

* Pass app, instead

Derived from https://github.com/facebook/create-react-app/issues/4492#issuecomment-421959548

Chrome requests `favicon.ico` on every route change, but stops if the `<link>` for it occurs early enough in the page. [Several](https://stackoverflow.com/questions/35409588/favicon-requested-on-every-route-change) other [people](https://github.com/ctrlplusb/react-universally/issues/145) have been running into this issue since at least February 2016.

* Tweak environment handling

* Add documentation for getCacheIdentifier

https://github.com/facebook/create-react-app/pull/5046#issuecomment-423501823

* support scoped packages for cra --scripts-version option

* cache yarn

* only cache yarn

* also cache .npm

* convert mocha tests to jest

* jest 23

* add jest configs

* use material css

* fix windows

* forceExit jest test

* force exit eject

* test

* test

* retrigger test

* remove appveyor comment

* try to remove pretendToBeVisual option

* use jsdom env

* test environment

* no cache

* test no close

* bring back raf

* test revert all broken changes

* add back jsdom

* remove jsdom

* node test environment

* use latest change

* runInBand

* runInBand

* comment test run

* try different jest option

* standardize jest test options

* increase heap size

* remove heap size config

* support scoped packages for cra --scripts-version option

* upgrade jest version

* fix windows

* fix windows again

* jest 23.4.1

* babel-jest

* babel-jest

* split out kitchhensink

* travis node 6

* travis node 6 config

* node 6 travis eject

* cache yarn

* only cache yarn

* remove unrelated changes

* typo

Adjust the default browsers to be a single list and remove it from the build output; it only affects CSS now

* Correct babel dependency compile target

* Correctly compile runtime for dependencies

This is the best behavior so people have seamless upgrades to new React majors.

This is probably a terrible default warning from the ESLint plugin, and we need to wait for https://github.com/yannickcr/eslint-plugin-react/issues/1955 before changing this hardcoded behavior.

Closes #5034

Closes #5020