Feature request: QualifyingElement tag whitelist

[deepfriedmind]

I think it would be great if one could provide a tag whitelist for the QualifyingElement linter. For example, I would like to be able to use a selector like html.no-csstransforms3d (because I prefer to be explicit in this case) without warnings, but have warnings enabled for all other tags.

[srawlins]

Not a bad idea. Consider Bootstrap's button styles which can be applied to <a>, <button>, and <input>, and there might be reasons to choose <a> in some cases and <input> in others... (is that true?), and then style a.btn differently from input.btn.

Same with other elements that play similar semantic roles but maybe should be styled differently, like <th> and <td>, or <p>, <li>, and <blockquote>. This is all pretty handwavey... I don't have any great examples.

[lencioni]

I think this makes sense. We'd be happy to accept a pull request that adds this functionality.