Clean up plugins (#14676)

Preparation for a larger rewrite

packages/next-plugin-material-ui/package.json

-{
-  "name": "@next/plugin-material-ui",
-  "version": "9.4.5-canary.22",
-  "repository": {
-    "url": "vercel/next.js",
-    "directory": "packages/next-plugin-material-ui"
-  },
-  "nextjs": {
-    "name": "Material UI",
-    "required-env": []
-  },
-  "peerDependencies": {
-    "@material-ui/styles": "*",
-    "next": "*",
-    "react": "*"
-  }
-}

packages/next-plugin-material-ui/readme.md

-# Unstable @next/plugin-material-ui
-
-This package is still very experimental and should not be used at this point

packages/next-plugin-material-ui/src/document-head-tags-server.js

-import React from 'react'
-
-export default async function headTags() {
-  return (
-    <>
-      <meta charSet="utf-8" />
-      <meta
-        name="viewport"
-        content="minimum-scale=1, initial-scale=1, width=device-width, shrink-to-fit=no"
-      />
-      <link
-        rel="stylesheet"
-        href="https://fonts.googleapis.com/css?family=Roboto:300,400,500,700&display=swap"
-      />
-    </>
-  )
-}

packages/next-plugin-material-ui/src/unstable-enhance-app-server.js

-import React from 'react'
-import { ServerStyleSheets } from '@material-ui/styles'
-
-export default async function enhanceApp(ctx) {
-  ctx.sheets = new ServerStyleSheets()
-  return (App) => (props) => ctx.sheets.collect(<App {...props} />)
-}

packages/next-plugin-material-ui/src/unstable-get-styles-server.js

-export default async function getStyles(ctx) {
-  return ctx.sheets.getStyleElement()
-}

packages/next-plugin-material-ui/src/unstable-post-hydration.js

-export default async function unstablePostHydration() {
-  // Remove the server-side injected CSS.
-  const jssStyles = document.querySelector('#jss-server-side')
-  if (jssStyles) {
-    jssStyles.parentNode.removeChild(jssStyles)
-  }
-}

packages/next/build/plugins/collect-plugins.ts

@@ -24,9 +24,6 @@ export const VALID_MIDDLEWARE = [
   'on-error-client',
   'on-error-server',
   'babel-preset-build',
-  'unstable-post-hydration',
-  'unstable-get-styles-server',
-  'unstable-enhance-app-server',
 ]
 
 type ENV_OPTIONS = { [name: string]: string }

packages/next/client/index.js

@@ -79,20 +79,6 @@ class Container extends React.Component {
   componentDidMount() {
     this.scrollToHash()
 
-    if (process.env.__NEXT_PLUGINS) {
-      // eslint-disable-next-line
-      import('next-plugin-loader?middleware=unstable-post-hydration!')
-        .then((mod) => {
-          return mod.default()
-        })
-        .catch((postHydrationErr) => {
-          console.error(
-            'Error calling post-hydration for plugins',
-            postHydrationErr
-          )
-        })
-    }
-
     // We need to replace the router state if:
     // - the page was (auto) exported and has a query string or search (hash)
     // - it was auto exported and is a dynamic route (to provide params)

packages/next/pages/_document.tsx

@@ -56,30 +56,12 @@ export default class Document<P = {}> extends Component<DocumentProps & P> {
   static async getInitialProps(
     ctx: DocumentContext
   ): Promise<DocumentInitialProps> {
-    const enhancers = process.env.__NEXT_PLUGINS
-      ? await import(
-          // @ts-ignore loader syntax
-          'next-plugin-loader?middleware=unstable-enhance-app-server!'
-        ).then((mod) => mod.default(ctx))
-      : []
-
     const enhanceApp = (App: any) => {
-      for (const enhancer of enhancers) {
-        App = enhancer(App)
-      }
       return (props: any) => <App {...props} />
     }
 
     const { html, head } = await ctx.renderPage({ enhanceApp })
-    const styles = [
-      ...flush(),
-      ...(process.env.__NEXT_PLUGINS
-        ? await import(
-            // @ts-ignore loader syntax
-            'next-plugin-loader?middleware=unstable-get-styles-server!'
-          ).then((mod) => mod.default(ctx))
-        : []),
-    ]
+    const styles = [...flush()]
     return { html, head, styles }
   }