Support un-'px'ed styles

[charliermarsh]

We should support the same CSS style objects as React. For example, we should allow for { width: 10} to be a valid style object.

In general, why don't we utilize CSSPropertyOperations.createMarkupForStyles to generate a string of CSS? We could call it after checking for pseudo-selectors and media queries, and performing whatever pre-processing we want to support. I've already implemented this and can merge it in, if you agree.

[charliermarsh]

The downsides of this approach:

1. React becomes an explicit dependency.
2. In order to use createMarkupForStyles, we actually need to require deep into the React source (semi-bad practice).

I'm not terribly concerned about (1) given that 99.9% of RCSS users will be using it with React anyway, but as an alternative, we could carve out the few files we need and start maintaining our own copies. Anyway, I still opt for using createMarkupForStyles as it'll keep us in-sync with React going forward.

[Raynos]

given that 99.9% of RCSS users will be using it with React

We are thinking of using RCSS with mercury at Uber. One of the projects that we have in mind is to publish a modular version of something like bootstrap build from the ground up in RCSS & virtual-dom.

I've done a bunch of experiments to see what's really needed to do this performantly with server side rendering, if you couple it to react it would be harder for us to collaborate.