Add allow-outside-scroll property

[mattprivman]

Adding an allow-scroll-lock property implemented in iron-dropdown PR #25, to make it accessible in paper-dropdown-menu. This depends on 'paper-menu-button' PR #35 being merged.

[cdata]

This PR needs a rebase.

[valdrinkoshi]

This now depends on PolymerElements/paper-menu-button#67 (because of all the rebases).
Once that is merged, we need to update the bower dependency of paper-dropdown-menu to depend on the correct minimum version of paper-menu-button

[valdrinkoshi]

@mattppp paper-menu-button v1.2.0 has been released, and it exposes allow-outside-scroll property. Could you update bower.json to require this version?

"paper-menu-button": "PolymerElements/paper-menu-button#^1.2.0",

[googlebot]

We found a Contributor License Agreement for you (the sender of this pull request), but were unable to find agreements for the commit author(s). If you authored these, maybe you used a different email address in the git commits than was used to sign the CLA (login here to double check)? If these were authored by someone else, then they will need to sign a CLA as well, and confirm that they're okay with these being contributed to Google.

[valdrinkoshi]

@mattppp looks like there are issues with the CLA signature. Could you squash the commits all in one and send it with your github user?

[mattprivman]

Not quite sure what's up with the CLA. It looks like it's signed from my end.

[valdrinkoshi]

I think the problem is due to the fact that you did the commit without signing as @mattppp

[googlebot]

CLAs look good, thanks!

[mattprivman]

Had an old email on the commit. Thanks for the help :)

[valdrinkoshi]

Awesome! Thanks for the contribution @mattppp!

[valdrinkoshi]

@mattppp, my bad, I just noticed this should be added also to paper-dropdown-menu-light :x
Would you mind doing it? Otherwise I can take care of it.