* Add deprecation warning for App Container
* Apply suggestions from code review
Co-Authored-By: Joe Haddad <joe.haddad@zeit.co>
* Tweak for more dead-code elimination
# Fixes https://github.com/zeit/next.js/issues/5674
This adds config option
```js
// next.config.js
module.exports = {
crossOrigin: 'anonymous'
}
```
This config option is defined in the webpack Define Plugin at build.
`Head` and `NextScript` now use the config option, if it's not explicitly set on the element.
This value is now passed to Webpack so it can add it to scripts that it loads.
The value is now used in `PageLoader` (on the client) so it can add it to the scripts and links that it loads.
Using `<Head crossOrigin>` or `<NextScript crossOrigin>` is now deprecated.
* Add support for custom App and Component enhancers
* Add ctx.renderPage test
* Add tests for single enhancer function
* Cleanup renderPage options check
* Cleanup
* Add comment about backwards compatibility for renderPage
* Add more test cases
* Expose pages/_app.js
* Add tests for _app and _document
* Uncomment deprecation warnings
* Add documentation for _app, improve documentation of _document
* Update docs / test for _document
* Add _document to client compiler in development
* Add missing app.js to comment
* Only warn once
* Add url-deprecated error page
* Combine tests
* Yse same message for all methods of ‘props.url’
* Update docs around _app
* Update documentation
* Quotes
* Update table of contents
