I just realised that the Web Components polyfills not only are in npm so you can install them like this:
npm install --save webcomponents-lite
but they also have a well formed package.json with a main entry.
So if you're writing your front-end code with Browserify and want to load the polyfill without adding an additional script tag, you can do this:
and this pulls the polyfill into the scope.
NICE! Thanks, Addy :-)
PS I guess this should also work with webpack, if you're so inclined.