* Drop ie 11 support and move polyfills to a new package

* More useful directions for what entry point to use
https://github.com/facebook/create-react-app/pull/5090#discussion_r220313783

* Clear up what file this polyfill goes in
https://github.com/facebook/create-react-app/pull/5090#discussion_r220313980

* Polyfill `window`, not `global`

* Remove proxy polyfill file

* File headers BSD+Patents -> MIT

* BSD+Patents -> MIT

* Remove unnecessary dependencies(#751)

* Sort alphabetically

* Add get-source-map tests

* Fixtures shouldn't be formatted

* Add mapper tests

* Add stack-frame tests

* Add more util tests

* Add unmapper tests

* Add parser tests

* Switch to snapshots

* Snapshot more

* ༼ 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 8bf601db.

* Remove broken script

* Fix some dev ergo