Centralize Babel's own compilation config to make it easier to follow. (#7599)

scripts/gulp-tasks.js

@@ -39,25 +39,18 @@ function webpackBuild(opts) {
           test: /\.js$/,
           loader: "babel-loader",
           options: {
+            // Use the bundled config so that module syntax is passed through
+            // for Webpack.
+            envName: "standalone",
+
             // Some of the node_modules may have their own "babel" section in
             // their project.json (or a ".babelrc" file). We need to ignore
             // those as we're using our own Babel options.
             babelrc: false,
-            presets: [
-              [
-                "@babel/env",
-                {
-                  loose: true,
-                  exclude: ["transform-typeof-symbol"],
-                },
-              ],
-            ],
-            overrides: [
-              {
-                exclude: /node_modules/,
-                presets: [["@babel/stage-0", { loose: true }]],
-              },
-            ],
+
+            // We explicitly load the `.babelrc.js` file since searching is
+            // turned off, but we still want to use the main config.
+            extends: "./.babelrc.js",
           },
         },
       ],