* Fixed several of the issues and nits from PR:

* Moved margin between header and file name to header, so when content was scrolled, the header would remain more separate
* Made build-time and runtime overlays better match
* Secondary error <pre> style now uses yellow bg instead of red
* 'Scrollable Header' (see above comment to why this is necessary) but I did increase the max-height from 35% to 50%.
* Fixed header and 'X' button vertical alignment

* Temporary stack margin fix

* Move "N errors" to the top

* Don't collapse unintentional top-level errors

* Linkify internal stack frames too

* Click to view source

* Update package.json

* Update package.json

* Fix lint

* ༼ 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