Properly attach middleware to webpack-dev-server

As shown in https://webpack.js.org/configuration/dev-server
middlewares should be added as an object with `name` and `middleware`
elements.

config/webpack.config.js

@@ -702,7 +702,10 @@ module.exports = {
       const incrementalCompilerMiddleware = incrementalCompiler.createMiddleware(devServer);
 
       if (incrementalCompilerMiddleware) {
-        middlewares.unshift(incrementalCompilerMiddleware);
+        middlewares.unshift({
+          name: 'incremental-compiler',
+          middleware: incrementalCompilerMiddleware,
+        });
       }
 
       return middlewares;