Button accessibility name doesn't indicate label element can be used

[mraccess77]

The label element seems to be usable to label buttons but this doesn't seem to be list in the accessible name calculation.

[jnurthen]

Also applies for <output> and all the other <input> types too

[carmacleod]

The inputs in section 4.1 (type="text", "password", "search", "tel", "url" and textarea element) do mention label, as follows:

2. Otherwise use the associated label element(s) accessible name(s) - if more than one label is associated; concatenate by DOM order, delimited by spaces.

But the inputs in section 4.2 (type="button", "submit", "reset") don't mention label. So we can reuse the above wording for those.

The HTML labelable elements are: button, input (if the type attribute is not in the Hidden state), meter, output, progress, select, textarea, and form-associated custom elements

So from that list, we need to add the point about label to:

• section 4.2 input type="button", "submit", "reset"
• section 4.3 input type="image"
• section 4.4 button element
• section 4.6 output element

Note that section 4.7 Other form elements also mentions label:

2. Otherwise use label element. (maybe this should have the same wording as section 4.1, above?)

Should we just assume that meter, progress, select, and FACE are lumped under "Other form elements", or should we call them out specifically? Also, should we specifically mention that input type="hidden" is not labelable?

[scottaohara]

started on this some time ago re #225. clearly never got to finishing it. spent a bunch of time trying to make sense of how some of the button labeling needed to work / make things consistent.

seems this would also touch on #210