menuitemcheckbox / menuitemradio do not inherit from input in ARIA 1.2

[WilcoFiers]

From @jnurthen

w3c/aria#1278 removes the multiple inheritance from menuitemcheckbox and menuitemradio such that this will no longer be true once this appears in a spec.

Content in the background section needs to be updated when we move to WAI-ARIA 1.2.

[WilcoFiers]

This was discussed on the ACT TF call. The conclusion there is that the rule "from field has accessible name" is not a good description of what the rule does. The correct title really is "input or select widget has accessible name", which suggests the problem with that particular rule; It combines testing roles that inherit from select, and that inherit from input in the same rule.

Thinking of this a little more systematically. I think once ARIA 1.2 is out, we should revisit the way these requirements are split up. I think the following breakdown makes the most sense:

1. Command widget has non-empty accessible name:

   • button
   • link
   • menuitem

2. Select widget has non-empty accessible name:

   • listbox
   • menu
   • radiogroup
   • tree

3. Input widget has non-empty accessible name:

   • checkbox
   • combobox
   • option
   • radio
   • slider
   • spinbutton
   • textbox

4. Range widget has non-empty accessible name: (This does not include all range, just ones that are also widgets)

   • progressbar
   • scrollbar
   • slider
   • spinbutton

5. Irregular widget has non-empty accessible name: (Widgets that do not inherit from command, select, input or range)

   • gridcell
   • row
   • separator
   • tab

[WilcoFiers]

For ARIA 1.2 we just need to update the background section to clarify that menuitem is also a role to consider.

[Jym77]

This was closed by #1942