Prefer builtin optional chaining and nullish coalescing (#16780)

Babel-preset-env includes includes optional chaining and
nullish-coalescing since [7.8.0](https://github.com/babel/babel/releases/tag/v7.8.0).

In this diff I removed these plugins from next preset to prevent
dependency duplication when their newer versions are out.

packages/next/build/babel/preset.ts

@@ -181,8 +181,6 @@ module.exports = (
           removeImport: true,
         },
       ],
-      require('@babel/plugin-proposal-optional-chaining'),
-      require('@babel/plugin-proposal-nullish-coalescing-operator'),
       isServer && require('@babel/plugin-syntax-bigint'),
       // Always compile numeric separator because the resulting number is
       // smaller.

packages/next/package.json

@@ -63,10 +63,8 @@
     "@babel/core": "7.7.7",
     "@babel/plugin-proposal-class-properties": "7.10.4",
     "@babel/plugin-proposal-export-namespace-from": "7.10.4",
-    "@babel/plugin-proposal-nullish-coalescing-operator": "7.10.4",
     "@babel/plugin-proposal-numeric-separator": "7.10.4",
     "@babel/plugin-proposal-object-rest-spread": "7.11.0",
-    "@babel/plugin-proposal-optional-chaining": "7.11.0",
     "@babel/plugin-syntax-bigint": "7.8.3",
     "@babel/plugin-syntax-dynamic-import": "7.8.3",
     "@babel/plugin-transform-modules-commonjs": "7.10.4",

packages/next/taskfile-babel.js

@@ -62,8 +62,6 @@ const babelServerOpts = {
     ],
   ],
   plugins: [
-    '@babel/plugin-proposal-optional-chaining',
-    '@babel/plugin-proposal-nullish-coalescing-operator',
     'babel-plugin-dynamic-import-node',
     ['@babel/plugin-proposal-class-properties', { loose: true }],
   ],

yarn.lock

@@ -643,7 +643,7 @@
     "@babel/helper-plugin-utils" "^7.10.4"
     "@babel/plugin-syntax-logical-assignment-operators" "^7.10.4"
 
-"@babel/plugin-proposal-nullish-coalescing-operator@7.10.4", "@babel/plugin-proposal-nullish-coalescing-operator@^7.10.4":
+"@babel/plugin-proposal-nullish-coalescing-operator@^7.10.4":
   version "7.10.4"
   resolved "https://registry.yarnpkg.com/@babel/plugin-proposal-nullish-coalescing-operator/-/plugin-proposal-nullish-coalescing-operator-7.10.4.tgz#02a7e961fc32e6d5b2db0649e01bf80ddee7e04a"
   integrity sha512-wq5n1M3ZUlHl9sqT2ok1T2/MTt6AXE0e1Lz4WzWBr95LsAZ5qDXe4KnFuauYyEyLiohvXFMdbsOTMyLZs91Zlw==
@@ -683,7 +683,7 @@
     "@babel/helper-plugin-utils" "^7.10.4"
     "@babel/plugin-syntax-optional-catch-binding" "^7.8.0"
 
-"@babel/plugin-proposal-optional-chaining@7.11.0", "@babel/plugin-proposal-optional-chaining@^7.11.0":
+"@babel/plugin-proposal-optional-chaining@^7.11.0":
   version "7.11.0"
   resolved "https://registry.yarnpkg.com/@babel/plugin-proposal-optional-chaining/-/plugin-proposal-optional-chaining-7.11.0.tgz#de5866d0646f6afdaab8a566382fe3a221755076"
   integrity sha512-v9fZIu3Y8562RRwhm1BbMRxtqZNFmFA2EG+pT2diuU8PT3H6T/KXoZ54KgYisfOFZHV6PfvAiBIZ9Rcz+/JCxA==