How do I load my own polyfill.ts file?

From Angular 2 doc

Polyfills should be bundled separately from the application and vendor bundles. Add a polyfills.ts like this one to the src/ folder.!#polyfills

entry: {
'polyfills': './src/polyfills.ts',
'vendor': './src/vendor.ts',
'app': './src/main.ts'

From Ionic 2 webpack.config.js

`entry: process.env.IONIC_APP_ENTRY_POINT`

What should I do to load my pollyfill.ts and not break Ionic 2?