disable webpack.optimize.ModuleConcatenationPlugin during karma tests only

config/karma.config.js

@@ -8,6 +8,7 @@ if (webpackConfig.plugins) {
   webpackConfig.plugins = webpackConfig.plugins.filter(function (plugin) {
     return !(
       plugin instanceof webpack.optimize.CommonsChunkPlugin ||
+      plugin instanceof webpack.optimize.ModuleConcatenationPlugin ||
       plugin instanceof webpack.DefinePlugin
     );
   });

config/webpack.config.js

@@ -234,7 +234,7 @@ var config = {
     }),
 
     // enable scope hoisting
-    // new webpack.optimize.ModuleConcatenationPlugin(),
+    new webpack.optimize.ModuleConcatenationPlugin(),
 
     // copy pre-compiled vendor libraries verbatim
     new CopyWebpackPlugin([