Use babel to transpile to javascript compatible with firefox 68

because we are still using it on tests machines

index.js

+import 'core-js/actual'; // BBB firefox 68
 import "./public-path.js"
 import * as monaco from 'monaco-editor';
 

package.json

@@ -5,7 +5,11 @@
     "deploy": "node deploy.js"
   },
   "devDependencies": {
+    "@babel/core": "^7.20.5",
+    "@babel/preset-env": "^7.20.2",
     "argparse": "^1.0.10",
+    "babel-loader": "^9.1.0",
+    "core-js": "^3.26.1",
     "css-loader": "^5.2.4",
     "file-loader": "^6.2.0",
     "monaco-editor": "latest",

webpack.config.js

@@ -25,7 +25,28 @@ module.exports = {
     }, {
       test: /\.ttf$/,
       use: ['file-loader']
-    }]
+    },
+    {
+      test: /\.m?js$/,
+      exclude: {
+        and: [/node_modules/],
+        not: [
+          /monaco-editor/,
+        ]
+      },
+      use: {
+        loader: 'babel-loader',
+        options: {
+          presets: [
+            ['@babel/preset-env', {
+              targets: { firefox: 68 },
+              corejs: "3"
+            }]
+          ],
+        }
+      }
+    }
+    ]
   },
   optimization: {
     minimize: true,