Currently when an img element has a title, aria-label or aria-labelledby and a supported role i.e. button we report it as a violation, this appears to be a false positive as we do not report it as a violation when an alt tag is added.

<img role="button" alt="foo" /> - pass
<img role="button" aria-label="foo" /> - fail

<div id="bar">hello world</div>
<img role="button" aria-labelledby="bar" /> - fail

we have added a new matcher to match an element that has a non-empty accessible name. By doing so gives us the ability to add a matches property on a new variant noAlt that will check if the img element text is accessible (in this case, title, aria-label and, aria-labelledby) if an alt tag is not present.

W3C resources provided by the by the author in #3143:
https://www.w3.org/TR/html-aria/#el-img-no-alt
https://www.w3.org/TR/html-aam-1.0/#img-element-accessible-name-computation
https://www.w3.org/TR/html-aria/#el-img

Closes issue: #3143