Remove inferno example (#9108)

examples/using-inferno/README.md

-# Inferno example
-
-> **Important**: Inferno does not support hooks nor Suspense. It may work on development where React is utilized instead of Inferno, but it will break as soon as you try to build it or start it out of development.
-
-## How to use
-
-### Using `create-next-app`
-
-Execute [`create-next-app`](https://github.com/zeit/next.js/tree/canary/packages/create-next-app) with [Yarn](https://yarnpkg.com/lang/en/docs/cli/create/) or [npx](https://github.com/zkat/npx#readme) to bootstrap the example:
-
-```bash
-npx create-next-app --example using-inferno using-inferno-app
-# or
-yarn create next-app --example using-inferno using-inferno-app
-```
-
-### Download manually
-
-Download the example:
-
-```bash
-curl https://codeload.github.com/zeit/next.js/tar.gz/canary | tar -xz --strip=2 next.js-canary/examples/using-inferno
-cd using-inferno
-```
-
-Install it and run:
-
-```bash
-npm install
-npm run dev
-# or
-yarn
-yarn dev
-```
-
-Deploy it to the cloud with [now](https://zeit.co/now) ([download](https://zeit.co/download))
-
-```bash
-now
-```
-
-## The idea behind the example
-
-This example uses [Inferno](https://github.com/infernojs/inferno), an insanely fast, 9kb React-like library for building high-performance user interfaces on both the client and server. Here we've customized Next.js to use Inferno instead of React in the production build.
-
-Here's how we did it:
-
-- Use `next.config.js` to customize our webpack config to support [inferno-compat](https://www.npmjs.com/package/inferno-compat)
-- Create `lib/inferno-compat.js` to polyfill the `React.createContext` API (required by Next.js) that is not available by `inferno-compat`

examples/using-inferno/lib/inferno-compat.js

-const React = require('inferno-compat')
-const createContext = require('create-react-context/lib/implementation')
-
-Object.keys(React).forEach(key => {
-  if (key === 'default' || key === '__esModule') return
-  exports[key] = React[key]
-})
-
-// bypass export of React.createContext
-exports.createContext = createContext
-exports.default = React.default

examples/using-inferno/next.config.js

-const path = require('path')
-
-module.exports = {
-  webpack: function (config, { dev }) {
-    // For the development version, we'll use React.
-    // Because, it support react hot loading and so on.
-    if (dev) {
-      return config
-    }
-
-    config.resolve.alias = {
-      ...config.resolve.alias,
-      react: path.resolve('./lib/inferno-compat.js'),
-      'react-dom': path.resolve('./lib/inferno-compat.js'),
-      'react-dom/server': 'inferno-server'
-    }
-
-    return config
-  }
-}

examples/using-inferno/package.json

-{
-  "name": "using-inferno",
-  "version": "1.0.0",
-  "scripts": {
-    "dev": "node server.js",
-    "build": "next build",
-    "start": "NODE_ENV=production node server.js"
-  },
-  "dependencies": {
-    "create-react-context": "0.3.0",
-    "inferno": "7.3.2",
-    "inferno-compat": "7.3.2",
-    "inferno-server": "7.3.2",
-    "module-alias": "^2.0.0",
-    "next": "latest",
-    "react": "^16.7.0",
-    "react-dom": "^16.7.0"
-  },
-  "license": "MIT"
-}

examples/using-inferno/pages/about.js

-import React from 'react'
-
-export default () => <div>About us</div>

examples/using-inferno/pages/index.js

-import React from 'react'
-import Link from 'next/link'
-
-export default () => (
-  <div>
-    Hello World.{' '}
-    <Link href='/about'>
-      <a>About</a>
-    </Link>
-  </div>
-)

examples/using-inferno/server.js

-const port = parseInt(process.env.PORT, 10) || 3000
-const dev = process.env.NODE_ENV !== 'production'
-const moduleAlias = require('module-alias')
-const path = require('path')
-
-// For the development version, we'll use React.
-// Because, it support react hot loading and so on.
-if (!dev) {
-  moduleAlias.addAlias('react', path.resolve('./lib/inferno-compat.js'))
-  moduleAlias.addAlias('react-dom/server', 'inferno-server')
-  moduleAlias.addAlias('react-dom', path.resolve('./lib/inferno-compat.js'))
-}
-
-const { createServer } = require('http')
-const { parse } = require('url')
-const next = require('next')
-
-const app = next({ dev })
-const handle = app.getRequestHandler()
-
-app.prepare().then(() => {
-  createServer((req, res) => {
-    const parsedUrl = parse(req.url, true)
-    handle(req, res, parsedUrl)
-  }).listen(port, err => {
-    if (err) throw err
-    console.log(`> Ready on http://localhost:${port}`)
-  })
-})