Option to ignore twice-hidden elements in a11y text algorithm

The following code gives a different result in Chrome than it does in Firefox and Safari:

```html

- Chrome 72: "A label"
- Firefox 62: "A label that is super .hidden{}"
- Safari 12.0: "A label that is super .hidden{}"

In the new a11y computation axe will produce the Firefox / Safari result, but there are use cases where it's beneficial to produce the Chrome result. It'd be good to have an `ignoreTwiceHidden` option to allow returning this minimal text.

Start from the new accessibility text computation and reproduce the HTML example to compare its output with Chrome, Firefox, and Safari. The work is done when an `ignoreTwiceHidden` option returns the minimal text, such as "A label", for the reported use case.

Written by the indexing model from the issue text.