Minify postcss parser

package.json

@@ -114,7 +114,8 @@
     "snapshot-diff": "0.4.0",
     "strip-ansi": "4.0.0",
     "tempy": "0.2.1",
-    "webpack": "3.12.0"
+    "terser-webpack-plugin": "1.4.1",
+    "webpack": "4.39.1"
   },
   "scripts": {
     "prepublishOnly": "echo \"Error: must publish from dist/\" && exit 1",

scripts/build/build.js

@@ -99,7 +99,7 @@ async function run(params) {
     await execa("rm", ["-rf", ".cache"]);
   }
 
-  const bundleCache = new Cache(".cache/", "v13");
+  const bundleCache = new Cache(".cache/", "v15");
   await bundleCache.load();
 
   console.log(chalk.inverse(" Building packages "));

scripts/build/bundler.js

@@ -159,7 +159,7 @@ function getWebpackConfig(bundle) {
   }
 
   const root = path.resolve(__dirname, "..", "..");
-  return {
+  const config = {
     entry: path.resolve(root, bundle.input),
     module: {
       rules: [
@@ -176,14 +176,25 @@ function getWebpackConfig(bundle) {
       path: path.resolve(root, "dist"),
       filename: bundle.output,
       library: ["prettierPlugins", bundle.name],
-      libraryTarget: "umd"
-    },
-    plugins: [
-      new webpack.DefinePlugin({
-        "process.env.NODE_ENV": JSON.stringify("production")
-      })
-    ]
+      libraryTarget: "umd",
+      // https://github.com/webpack/webpack/issues/6642
+      globalObject: 'new Function("return this")()'
+    }
   };
+
+  if (bundle.terserOptions) {
+    const TerserPlugin = require("terser-webpack-plugin");
+
+    config.optimization = {
+      minimizer: [
+        new TerserPlugin({
+          terserOptions: bundle.terserOptions
+        })
+      ]
+    };
+  }
+
+  return config;
 }
 
 function runWebpack(config) {

scripts/build/config.js

@@ -15,6 +15,7 @@ const PROJECT_ROOT = path.resolve(__dirname, "../..");
  * @property {string[]} externals - array of paths that should not be included in the final bundle
  * @property {Object.<string, string>} replace - map of strings to replace when processing the bundle
  * @property {string[]} babelPlugins - babel plugins
+ * @property {Object?} terserOptions - options for `terser`
 
  * @typedef {Object} CommonJSConfig
  * @property {Object} namedExports - for cases where rollup can't infer what's exported
@@ -59,7 +60,13 @@ const parsers = [
     input: "src/language-css/parser-postcss.js",
     target: "universal",
     // postcss has dependency cycles that don't work with rollup
-    bundler: "webpack"
+    bundler: "webpack",
+    // postcss need keep_fnames when minify
+    terserOptions: {
+      mangle: {
+        keep_fnames: true
+      }
+    }
   },
   {
     input: "src/language-graphql/parser-graphql.js",