Rule proposal: buttons should have type specified

[bbarry]

We repeatedly are finding that a developer here or there has forgotten to add a type attribute to <button> tags in templates. Doing so causes buttons to trigger form submit events when they complete and happen to have an ancestor element that is a form tag. This may result in unintended code executing when someone presses the button. Additionally a browser or assisting device might choose to trigger the button to activate when a person submits from within a field in the form.

Valid code:

    <button type="submit" ...
    <button type="button" ...
    <button type="reset" ...

invalid:

    <button>
    <button type="">
    <button type="somethingelse">

[chernodub]

I've created a PR on this, please check