Non-Firefox browsers dispatch "click" on descendants of <button>, which breaks
the submitHandler logic that adds a hidden field with the name and value of the
submit button (since it is not included in the submission if it did not
initiate the submission, which might be the case when using form.submit in
submitHandler and returning false). submitButton is instead a descendant of
<button> and the hidden field does not compensate for the lack of an actual
submit button.

This would fix crbug.com/668524 and make submitButton an actual button.

For testing that clicking on descendants of a button element still keeps the button element as the submit button.

For testing that clicking on descendants of a button element still
keeps the button element as the submit button.

Accidental copy-paste.

Forgot to wrap the parenthesized value with spaces.

Forgot to wrap a parenthesized value with spaces.

Forgot to add a blank line above a comment.

Replaced a complex event initiation with a basic click().

Removed extraneous trailing spaces.

Removed two unused variables.

Instead of returning a DOM element, a jQuery element was returned.
Changed to return the original element in the target is already a button case.

Instead of looking for the parent or ancestor of the target,
just used the currentTarget property.

Devised by @Arkni.