paper-checkbox triggers _forwardInstanceProp on checked attribute when placed in template when initialized

[David-Mulder]

As per title, when I place a <paper-checkbox> inside a <template> it will trigger the _forwardInstanceProp with initialized checked state, whilst other elements do not do this. When I tried reproducing this in a simple scenario (with Templatizr) both seemed to behave exactly the same way (triggering listeners and the like at the same points), however in conjuction with Templatizr there is a difference somewhere.

[David-Mulder]

Nevermind, shame on me, it seems to do with the way undefined is handled when set on a paper-checkbox which is probably (and correctly) undefined behaviour.