Reuse .visually-hidden core functional class

Thank you! I've added couple of comments.

In fact i would better to discuss it.

@ckrina

I think CSS solution of duplication .visually-hidden CSS properties looks cleaner than JS extra search of that labels.
Probably better to keep it as is.

Addressed feedbacks in MR

May be a stretch but seems like something that a simple assertion could be added to a test.

I was the one who asked for this, but I agree with #8
It's a shame we don't use https://www.npmjs.com/package/postcss-mixins because this would be a good case for it.

It's also a shame there's no display: visually-hidden in the platform, but I see there are folks proposing it so perhaps at some point we will be able to ditch this.