##<iron-input>
<iron-input> adds two-way binding and custom validators using Polymer.IronValidatorBehavior
to <input>.
By default you can only get notified of changes to an input's value due to user input:
<input value="{{myValue::input}}">iron-input adds the bind-value property that mirrors the value property, and can be used
for two-way data binding. bind-value will notify if it is changed either by user input or by script.
<input is="iron-input" bind-value="{{myValue}}">You can use custom validators that implement Polymer.IronValidatorBehavior with <iron-input>.
<input is="iron-input" validator="my-custom-validator">It may be desirable to only allow users to enter certain characters. You can use the
prevent-invalid-input and allowed-pattern attributes together to accomplish this. This feature
is separate from validation, and allowed-pattern does not affect how the input is validated.
<!-- only allow characters that match [0-9] -->
<input is="iron-input" prevent-invalid-input allowed-pattern="[0-9]">