Fixes Auto-Validation fires directly for required without any user interaction

[aarondrabeck]

This resolves issues 134 and 655 introduced from PR 130.

Allowing '' here (along with undefined) should not create any issues because it is only checking once on startup. The alternative is to revert PR 130 but I am not sure why setting a default was needed.

[e111077]

Come think of it, why would the default value ever be undefined with the change in PolymerElements/iron-input#130? In polymer 1 it is a native input that is extended so it would be '' and polymer 2 we set it to '' in iron-input

[e111077]

A test would also be helpful to make sure this regression doesn't happen again

[aarondrabeck]

@notwaldorf Thanks for the merge and test! Is there any way we could get a release with this in it?

[e111077]

We are currently reviewing our internal test suite results. You should expect a release later today or a rollback depending on the result

[aarondrabeck]

Thanks!