Polymer/polymer-dev — pull request #70 by jakemac53 (2014-08-11 19:01:03+00:00)
Title: change layout.html to layout.css

I don't know if there is a reason this was an html import before, but it seems like it should just be a stylesheet. I did some quick testing and the shim-shadowdom attribute seems to work on a tag as well, and the vulcanizer will retain it when inlined.