feat(object-alt,accessible-text): object-alt rule and accessible text to work with serial virtual nodes with children

[straker]

There is a lot going on here but it was all necessary to get a serial virtual node with children to run through the accessbile-text functions. This allows object-alt and other rules that look at the subtree text to pass/fail with a full descendant tree (before it would just incomplete).

var node = new axe.SerialVirtualNode({
  nodeName: 'object'
});
var child = new axe.SerialVirtualNode({
  nodeName: '#text',
  nodeType: 3,
  textContent: 'foobar'
});
node.children.push(child);

var results = axe.runVirtualRule('object-alt', node);  // passes

We decided that if a virtual node does not have an actualNode property, we will always consider it visible so we don't have to enter the isVisible function which checks visibility with CSS.

We also needed serial virtual nodes to have text children, so they needed to accept nodeType of 3.

Note: I wanted to use the html-elm spec to know if the element was as phrasing element rather than keep that hardcoded list. Unfortunately our hardcoded list is not a complete list and so something like and input, which is a phrasing element, would no longer add space between the label text and the input value such as this acceptance test:

<label for="test">
  foo
  <input type="text" value="David"/>
</label>

Which results in fooDavid rather than foo David. So I had to leave it in, but had to lowercase the names, and also decided to sort the list while I was there (much easier to compare against the list in the spec).

This also lead to discovering some of the html-elm spec was incorrect, like kbd being misspelled and p and summary being phrasing elements when they should not have been. Also made namingMethods an array because it made more sense than being a string or array.

Part of issue #2183

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[WilcoFiers]

Oof! Good catch.

[WilcoFiers]

Why this change?

[straker]

like kdb misspelling, it's a correct to the file as 'summary' is not phrasing or flow content.

[WilcoFiers]

Why this change?

[straker]

like kdb misspelling, it's a correct to the file as 'p' is not phrasing content.

[WilcoFiers]

I love this utility. This is so useful!

Resolved