##<gold-cc-expiration-input>
gold-cc-expiration-input is a single-line text field with Material Design styling
for entering a credit card's expiration date
<gold-cc-expiration-input></gold-cc-expiration-input>
<gold-cc-expiration-input value="11/15"></gold-cc-expiration-input>It may include an optional label, which by default is "Expiration Date".
<gold-cc-expiration-input label="Date"></gold-cc-expiration-input>Validation
The input can check whether the entered date is a valid, future date.
The input can be automatically validated as the user is typing by using
the auto-validate and required attributes. For manual validation, the
element also has a validate() method, which returns the validity of the
input as well sets any appropriate error messages and styles.
See Polymer.PaperInputBehavior for more API docs.
Styling
See Polymer.PaperInputContainer for a list of custom properties used to
style this element.