Fixes LIT_TYPES_REGISTRY in OSS builds by preserving TS/JS class names

PiperOrigin-RevId: 470740806

lit_nlp/client/webpack/config.js

@@ -19,6 +19,7 @@ const glob = require('glob');
 const path = require('path');
 const webpack = require('webpack');
 const FileManagerPlugin = require('filemanager-webpack-plugin');
+const TerserPlugin = require("terser-webpack-plugin");
 
 const GLOB_OPTIONS = {
   ignore: ['**/*test.ts', '**/*test.js', '**/testing_utils.ts']
@@ -109,7 +110,7 @@ module.exports = (env = {}) => {
   }
 
   return {
-    mode: 'development',
+    mode: isProd ? 'production' : 'development',
     devtool: 'source-map',
     module: {
       rules: [
@@ -135,6 +136,19 @@ module.exports = (env = {}) => {
         },
       ],
     },
+    optimization: {
+      minimize: isProd,
+      minimizer: [
+        new TerserPlugin({
+          cache: true,
+          parallel: true,
+          sourceMap: true,
+          terserOptions: {
+            keep_classnames: true   // Required for LIT_TYPES_REGISTRY to work
+          }
+        })
+      ]
+    },
     resolve: {
       modules: ['node_modules'],
       extensions: ['.ts', '.js'],