Performance improvement: stop serving wrapper code (#179)

* Only serve react app in development

- Don't serve server code from "webpack serve"
- Don't serve iframe wrapper from "webpack serve"
- Update "basic" local test to load -impl file, not wrapper

webpack.config.js

@@ -25,6 +25,8 @@ envVars.NODE_ENV = process.env.NODE_ENV;
 envVars.PORT = PORT;
 
 const isProd = process.env.NODE_ENV === 'production';
+const isWebpackServe = process.env.WEBPACK_SERVE === 'true';
+
 const publicPath = process.env.ASSET_PATH || '/';
 
 /*********************************
@@ -387,10 +389,11 @@ module.exports = [
   // 2. Set up webpack dev server during development
   // Note: devServer settings are only read in the first element when module.exports is an array
   { ...copyFilesConfig, ...(isProd ? {} : { devServer }) },
-  // 3. Create the server bundle
-  serverConfig,
+  // 3. Create the server bundle. Don't serve server bundle when running webpack serve.
+  !isWebpackServe && serverConfig,
   // 4. Create one client bundle for each client entrypoint.
   ...clientConfigs,
-  // 5. Create a development dialog bundle for each client entrypoint during development.
-  ...(isProd ? [] : devClientConfigs),
-];
+  // 5. Create a development dialog wrapper bundle for each client entrypoint during development.
+  //    Don't actually serve it though when running webpack serve.
+  ...(isProd || isWebpackServe ? [] : devClientConfigs),
+].filter(Boolean);