custom validator and other validators

[Mipme]

At the moment it seems not possible to have a custom validator and other validators like minlength and maxlength; It's also not possible to chain multiple validators.

Example:
<iron-input minlength="5" validator="slugOrEmailValidator"></iron-input>

The custom validator is triggered, but the minlength is not checked.
For the other case it would be feasable to set an Array as the validator attribute.