<iron-form> is a wrapper around the HTML <form> element, that can
validate and submit both custom and native HTML elements.
It has two modes: if allow-redirect is true, then after the form submission you
will be redirected to the server response. Otherwise, if it is false, it will
use an iron-ajax element to submit the form contents to the server.
Example:
<iron-form>
<form method="get" action="/form/handler">
<input type="text" name="name" value="Batman">
<input type="checkbox" name="donuts" checked> I like donuts<br>
<paper-checkbox name="cheese" value="yes" checked></paper-checkbox>
</form>
</iron-form>By default, a native <button> element (or input type="submit") will submit this form. However, if you
want to submit it from a custom element's click handler, you need to explicitly
call the iron-form's submit method.
Example:
<paper-button raised onclick="submitForm()">Submit</paper-button>
function submitForm() {
document.getElementById('iron-form').submit();
}