Inaccurate error message when `<a>` has images with `usemap` attribute
For example, given this HTML:
<a href=""><img src="#" alt="foo" usemap=""></a>
HTML-Validate with the element-permitted-content
rule enabled will report:
1:13 error <img> element is not permitted as a descendant of <a> element-permitted-content
But for more accuracy, the error message should describe that the problem is not the <img>
element itself but the usemap
attribute.