Helper elements to load polymer elements asynchronously.
There are lots of errors that get thrown when async flag is used for polymer references. See examples here. Apparently, some of these are caused by a bug in chrome. Perhaps when that bug is fixed, there will be no need for this component.
First, make sure you have the Polymer CLI installed. Then run polymer serve to serve your element locally.
$ polymer serve
$ polymer test
Your application is already set up to be tested via web-component-tester. Run polymer test to run your application's test suite locally.