You have to copy the whole js-webshim folder into your project. Currently you only have included polyfiller.js. This script only handles the polyfills and includes them from the shim folder.
If you open up your developer console, you will see that you have a lot of 404 requests for js/shims...js.
Some notes as long as you are using only form you should use webshims.polyfill('forms') or webshims.polyfill('forms forms-ext') and not webshims.polyfill(). If you have still problems, you should use the files from the dev folder and open your console.