Can i use the input type="date" polyfill of webshim without depending on GPL or closed licenses?

I would like to use the input type "date" polyfill of webshim. But i will not be allowed to depend on GPL or closed licenses for this project. Is there a way to only depend on the parts necessary for the forms and forms-ext polyfills and avoid the GPL licensed dependencies of webshim?

I only want to use this:

<input type="date" ng-model="scheduleDate" required>

<script>
   webshims.setOptions('forms-ext', {types: 'date'});
   webshims.polyfill('forms forms-ext');
</script>

I have seen this question: What is the minimal code I need to include from Webshim to get HTML5 date input to work?

But i am still unsure if there are any GPL or closed dependencies left in the scenario discussed.