Resolves#4055
Credit: https://github.com/zeit/next.js/pull/5095
I didn't use the ignore webpack plugin from the original PR and tested bundle size with https://github.com/zeit/next.js/pull/5339 - seems to be safe on that front.
Was able to get tests to pass locally, unsure of what goes wrong in CI 🤷♂️
**Questions**
1) The initial PR didn't include changes to `next-server/lib/router` in `getRouteInfo()`. Should the same changes be made within?
2) Should we add a test for rendering a component created via `forwardRef()`?
`component-with-forwardedRef`:
```javascript
export default React.forwardRef((props, ref) => <span {...props} forwardedRef={ref}>This is a component with a forwarded ref</span>);
```
some test:
```javascript
test('renders from forwardRef', async () => {
const $ = await get$('/component-with-forwardedRef')
const span = $('span')
expect(span.text()).toMatch(/This is a component with a forwarded ref/)
})
```
* Convert render.js to typescript
* Compile tsx files too
* Remove internal renderErrorToHTML function
* Interopt component result
* requirePage doesn’t need async
* Move out enhancing logic into it’s own function
* Remove buildManifest from renderPage
* Move render into it’s own function
* Change let to const
* Move renderDocument into it’s own function
