slash key should move input to year field

[austingreco]

When filling out an expiration date it would be nice if typing 1/16 would work just like 1 Tab 16

[notwaldorf]

Thanks a lot for filing this issue! Would you like to write a patch for this? We'd be more than happy to walk you through the steps involved.

[austingreco]

I'm not sure if this is the right way to do this (using iron-a11y-keys). Let me know if there's a better way.

Also attempted to write a test for this but ran into this issue: PolymerElements/iron-test-helpers#33