Misc. tweaks to improve webpack performance (#2994)

* Misc. tweaks to improve webpack performance

* Fix code climate style issues

superset/assets/package.json

@@ -12,7 +12,7 @@
     "cover": "babel-node node_modules/.bin/babel-istanbul cover _mocha -- --require spec/helpers/browser.js --recursive spec/**/*_spec.*",
     "dev": "NODE_ENV=dev webpack --watch --colors --progress --debug --output-pathinfo --devtool inline-source-map",
     "prod": "NODE_ENV=production node --max_old_space_size=4096 ./node_modules/webpack/bin/webpack.js -p --colors --progress",
-    "build": "NODE_ENV=production webpack --colors --progress",
+    "build": "NODE_ENV=production webpack --colors --progress &> /tmp/webpack.log",
     "lint": "eslint --ignore-path=.eslintignore --ext .js,.jsx .",
     "sync-backend": "babel-node --presets es2015 javascripts/syncBackend.js"
   },

superset/assets/webpack.config.js

@@ -125,6 +125,17 @@ const config = {
   ],
 };
 if (process.env.NODE_ENV === 'production') {
-  config.plugins.push(new webpack.optimize.UglifyJsPlugin());
+  config.plugins.push(
+    // Using settings suggested in https://github.com/webpack/webpack/issues/537
+    new webpack.optimize.UglifyJsPlugin({
+      sourceMap: false,
+      minimize: true,
+      compress: {
+        drop_debugger: true,
+        warnings: false,
+        drop_console: true,
+      },
+    }),
+  );
 }
 module.exports = config;