I implemented next set of Polymer web components from GWT Vaadin Polymer demo. Demo version on Heroku platform is available here, full source code here. I added the rest of components for Paper elements, also Iron and Vaadin elements. Not everything is working perfectly, but the main bulk of work is done.
Next step
I'm going to implement full support for list utilizing Vaadin grid components. I'm also inclined to rewrite all logic related to user interface. Assuming that user interface is supposed to be entirely Polymer-based, a lot of code supporting standard GWT widgets is out of use.
