Enhancement: Add CSS *definition* altering capabilities

[mistergibson]

I cobbled some simple code together that allows me to cache, create, update, and remove CSS rules of the page itself. I want you to take this code and incorporate something based upon it into your Browser::CSS tool set. Setting DOM Element style attributes is cool, but this gives you the ability to animate things by just hacking the CSS rules themselves. I hope you find it useful.

Code: https://gist.github.com/mistergibson/0393c96978fd2b1a09d6b0612af191f0

[hmdne]

From what I know, Opal-Browser HAS a preliminary implementation of this. I will inspect and look if this is a really viable, but seems like we already have some implementation in the css/ directory.