When there is a DOM element with id of `process`, the DOM marks it as a global, so `window.process` would exist. We should check for `process.env` to make sure it is available too.
This adds generating a static 500 status page when a `pages/500.js` file is added similar to how we handle generating static 404 pages when `pages/404.js` is present. This allows showing a customized error page when a 500 error occurs in an optimal way.
* Polyfilling fetch and object-assign
* Polyfilling corejs object-assign
* Adding object-assign in polyfills.js. IE11 does not support Object.assign
* Fixing failing test
* Updating object.assign polyfill to fix aliasing
* Updating test case value to match new build stats
* Increasing the size of default build to 225kb
* Fixing defer-script test case to not include polyfill.js
* Revert README.md
* Re-design the polyfill approach based on PR feedback
* Adding comment and fixing test case
* Rename polyfills chunk
* Extract aliases into helper
* Remove extra new line
* Fix TypeScript typings
* Adding _internal_fetch alias
* Adjust build manifest plugin
* Build manifest plugin changes - adding a separate entry for polyfills
* Rename polyfills entry in build-manifest.json
* Remove old comment
* Fix TS
* Set key
* Polyfills already added
* Filtring polyfill.module.js
* Fix test
* Add __internal_fetch to alias rule
* Adjust name
* bump size
* ignore polyfills
* sigh
* Aliasing Object.assign
* Mergin latest changes
* Integration test for polyfilling fetch
* Remove comment
* Fix prettier error
* Fix review comments
* Fix review comments
* Update fetch.js
* Fix tests
