feat(build) use core-js to polyfill modern JavaScript features

This should prevent us accidentally breaking compatibility with older
browsers because polyfilling happens automatically based on usage
detection.

app.js

 /* Jitsi Meet app main entrypoint. */
 
-// Polyfill Promise.withReolvers.
-// FIXME(saghul) webpack + core-js v3 should polyfill this.
-import 'promise.withresolvers/auto';
-
 // Re-export jQuery
 // FIXME: Remove this requirement from torture tests.
 import $ from 'jquery';

package-lock.json

         "babel-plugin-optional-require": "0.3.1",
         "circular-dependency-plugin": "5.2.0",
         "clean-css-cli": "4.3.0",
+        "core-js": "3.40.0",
         "css-loader": "6.8.1",
         "eslint": "8.57.0",
         "eslint-plugin-import": "2.31.0",
         "toggle-selection": "^1.0.6"
       }
     },
+    "node_modules/core-js": {
+      "version": "3.40.0",
+      "resolved": "https://registry.npmjs.org/core-js/-/core-js-3.40.0.tgz",
+      "integrity": "sha512-7vsMc/Lty6AGnn7uFpYT56QesI5D2Y/UkgKounk87OP9Z2H9Z8kj6jzcSGAxFmUtDOS0ntK6lbQz+Nsa0Jj6mQ==",
+      "dev": true,
+      "hasInstallScript": true,
+      "license": "MIT",
+      "funding": {
+        "type": "opencollective",
+        "url": "https://opencollective.com/core-js"
+      }
+    },
     "node_modules/core-js-compat": {
       "version": "3.38.1",
       "resolved": "https://registry.npmjs.org/core-js-compat/-/core-js-compat-3.38.1.tgz",
         "toggle-selection": "^1.0.6"
       }
     },
+    "core-js": {
+      "version": "3.40.0",
+      "resolved": "https://registry.npmjs.org/core-js/-/core-js-3.40.0.tgz",
+      "integrity": "sha512-7vsMc/Lty6AGnn7uFpYT56QesI5D2Y/UkgKounk87OP9Z2H9Z8kj6jzcSGAxFmUtDOS0ntK6lbQz+Nsa0Jj6mQ==",
+      "dev": true
+    },
     "core-js-compat": {
       "version": "3.38.1",
       "resolved": "https://registry.npmjs.org/core-js-compat/-/core-js-compat-3.38.1.tgz",

package.json

     "babel-plugin-optional-require": "0.3.1",
     "circular-dependency-plugin": "5.2.0",
     "clean-css-cli": "4.3.0",
+    "core-js": "3.40.0",
     "css-loader": "6.8.1",
     "eslint": "8.57.0",
     "eslint-plugin-import": "2.31.0",

react/features/stream-effects/virtual-background/index.ts

 import logger from '../../virtual-background/logger';
 
 import JitsiStreamBackgroundEffect, { IBackgroundEffectOptions } from './JitsiStreamBackgroundEffect';
-// @ts-expect-error
+// @ts-ignore
 import createTFLiteModule from './vendor/tflite/tflite';
-// @ts-expect-error
+// @ts-ignore
 import createTFLiteSIMDModule from './vendor/tflite/tflite-simd';
 const models = {
     modelLandscape: 'libs/selfie_segmentation_landscape.tflite'

react/features/stream-effects/virtual-background/vendor/tflite/tflite-simd.js

 }
 );
 })();
-if (typeof exports === 'object' && typeof module === 'object')
-  module.exports = createTFLiteSIMDModule;
-else if (typeof define === 'function' && define['amd'])
-  define([], function() { return createTFLiteSIMDModule; });
-else if (typeof exports === 'object')
-  exports["createTFLiteSIMDModule"] = createTFLiteSIMDModule;
+
+export default createTFLiteSIMDModule;

react/features/stream-effects/virtual-background/vendor/tflite/tflite.js

 }
 );
 })();
-if (typeof exports === 'object' && typeof module === 'object')
-  module.exports = createTFLiteModule;
-else if (typeof define === 'function' && define['amd'])
-  define([], function() { return createTFLiteModule; });
-else if (typeof exports === 'object')
-  exports["createTFLiteModule"] = createTFLiteModule;
+
+export default createTFLiteModule;

webpack.config.js

                                     electron: 10,
                                     firefox: 68,
                                     safari: 14
-                                }
+                                },
 
+                                // Consider stage 3 proposals which are implemented by some browsers already.
+                                shippedProposals: true,
+
+                                // Detect usage of modern JavaScript features and automatically polyfill them
+                                // with core-js.
+                                useBuiltIns: 'usage',
+
+                                // core-js version to use, must be in sync with the version in package.json.
+                                corejs: '3.40'
                             }
                         ],
                         require.resolve('@babel/preset-react')
                 ...config.plugins,
                 ...getBundleAnalyzerPlugin(analyzeBundle, 'external_api')
             ],
-            performance: getPerformanceHints(perfHintOptions, 40 * 1024)
+            performance: getPerformanceHints(perfHintOptions, 85 * 1024)
         }),
         Object.assign({}, config, {
             entry: {