Added worker build script

scripts/webpack.config.worker.prod.js

@@ -0,0 +1,27 @@
+const path = require('path');
+const common = require('./webpack.config.common');
+
+const genConfig = ({
+  entry, filename, library, libraryTarget,
+}) => ({
+  ...common,
+  mode: 'production',
+  devtool: 'source-map',
+  target: 'webworker',
+  entry,
+  output: {
+    path: path.resolve(__dirname, '..', 'dist'),
+    filename,
+    library,
+    libraryTarget,
+  },
+});
+
+module.exports = [
+  genConfig({
+    entry: path.resolve(__dirname, '..', 'src', 'index.js'),
+    filename: 'ffmpeg.min.js',
+    library: 'FFmpeg',
+    libraryTarget: 'umd',
+  }),
+];