Form elements should be able to be labeled via encapsulation

[JAWS-test]

Currently only some form elements can be labeled via encapsulation, but not all of them. For example, slider and combobox are missing. Is there a reason for this? If not, for consistency within ARIA, but also for consistency to HTML, all form elements should be able to be labeled like this

[joanmarie]

Marking for 1.3 because not in the stable/working-draft for 1.2

[jnurthen]

closing as name form encapsulation has been dropped