Some configurations break `dom-template`

[cdata]

It is possible for some configurations of elements to break when using dom-template to stamp some DOM. dom-template attempts to notify the "parent" context of property changes, and ends up effectively trying if(foo in undefined) { ... }, which throws.

[parioux]

Had the same problem while writing a test ...
Got around it by setting the _parentProps property to an empty object (crashes in notifyPath function).
Found the workaround by looking at the commits of app-route mentioned here.

var tmpl = document.querySelector('#my-test-fixture').fixtureTemplates[0];
tmpl._parentProps = {};