Focused radio buttons don't submit form on Enter

[mlibby]

To reproduce:
Construct a <form> with md-radio-group any positive number of md-radio-button elements and a submit button.
Use the keyboard to focus the radio button group.
Press Enter.
Notice that the submit button is not activated.

Expected result:
The submit button should be activated.

Rationale:
Typical user agent behavior for forms is that pressing Enter while focused on a form element triggers an "implicit" submit (activate the submit button, if one is available). This is the behavior of the native control in Firefox and Chrome. http://www.w3.org/TR/html5/forms.html#implicit-submission

[marcysutton]

Confirmed this behavior: http://codepen.io/marcysutton/pen/GgqQqQ

[mh03r932]

I think there is still a problem with md-radio-groups and form submission.

When there is no ng-submit handler configured directly on the form but there is a button with type=submit then the angular specification says that the click handler of the first type="submit" button should be triggered when pressing enter (see https://docs.angularjs.org/api/ng/directive/form section "Submitting a form and preventing the default action").

This works for normal input elements but not for md-radio-buttons.

JS Fiddle to demonstrate the issue:
http://jsfiddle.net/hh5xh7gf/

1. focus radio-button
2. press enter

Maybe this issue could be reopend?

I think in radioButton.js the keydownListener() function should be appended by something along the following lines
let formElement: IAugmentedJQuery = angular.element(this.$mdUtil.getClosest(element[0], 'form')); nextButtons = formElement.children().find('input[type="submit"], button[type="submit"]'); if(nextButtons){ nextButtons.first().click(); }

in the KEY_DOWN_ENTER case.