chore: separate polyfill

build/webpack.polyfill.js

@@ -0,0 +1,10 @@
+const path = require('path')
+
+module.exports = {
+  mode: 'production',
+  entry: './src/polyfill',
+  output: {
+    path: path.resolve(__dirname, '../dist'),
+    filename: 'eruda-polyfill.js',
+  },
+}