Add react-error-overlay package (#2111)

* ༼ つ ◕_◕ ༽つ stack-frame-overlay

* Fix linting

* Remove auto overlay

* Fix e2e

* Pull in the rest

* Appease flow

* Correct dep

* Remove old repo references

* Check flow on test

* Test overlay in e2e

* Add cross env

* Rename package

* Make sure it gets built post-install

* Update the README

* Remove extra builds now that there's a postinstall script

* Revert "Remove extra builds now that there's a postinstall script"

This reverts commit 8bf601dbd36c1e0da7f785fa9ade70ab08ed8772.

* Remove broken script

* Fix some dev ergo

packages/react-scripts/config/webpack.config.dev.js

@@ -55,7 +55,7 @@ module.exports = {
     // We ship a few polyfills by default:
     require.resolve('./polyfills'),
     // Errors should be considered fatal in development
-    require.resolve('react-dev-utils/crashOverlay'),
+    require.resolve('react-error-overlay'),
     // Finally, this is your app's code:
     paths.appIndexJs,
     // We include the app code last so that if there is a runtime error during