Fix example and legacy build with nodejs 16.6

config/webpack-config-legacy-build.mjs

@@ -0,0 +1,56 @@
+import TerserPlugin from 'terser-webpack-plugin';
+import path, {dirname} from 'path';
+import {fileURLToPath} from 'url';
+
+const baseDir = dirname(fileURLToPath(import.meta.url));
+
+export default {
+  entry: './build/index.js',
+  devtool: 'source-map',
+  mode: 'production',
+  target: ['web', 'es5'],
+  module: {
+    rules: [
+      {
+        test: /^((?!es2015-)[\s\S])*\.js$/,
+        use: {
+          loader: 'buble-loader',
+          options: {
+            transforms: {dangerousForOf: true},
+          },
+        },
+        include: [
+          path.join(
+            baseDir,
+            '..',
+            'node_modules',
+            '@mapbox',
+            'mapbox-gl-style-spec'
+          ),
+        ],
+      },
+    ],
+  },
+  resolve: {
+    alias: {
+      ol: path.resolve('./build/ol'),
+    },
+  },
+  optimization: {
+    minimizer: [
+      new TerserPlugin({
+        terserOptions: {
+          // Mangle private members convention with underscore suffix
+          mangle: {properties: {regex: /_$/}},
+        },
+      }),
+    ],
+  },
+  output: {
+    path: path.resolve('./build/legacy'),
+    filename: 'ol.js',
+    library: 'ol',
+    libraryTarget: 'umd',
+    libraryExport: 'default',
+  },
+};