Use only public API in CSSProperty-test

[ksvitkovsky]

As a part of #9955

[gaearon]

Can we also have a second test that verifies they get correctly set when rendering on the client side with ReactDOM? In fact I think it might be best to remove this file and create a similar test inside ReactDOMServerIntegration-test that verifies these styles end up being set. Because it tests both client and server rendering at the same time.

[ksvitkovsky]

I'm working on it right now and have that weird issue(?) when rendering element with styles that has ms-prefixed rules. Rendered element' style property has ms-prefixed rules starting with lower-case 'm' in clean client render-scenario, while in others it is upper-case 'M'.

Is that the expected behavior? If so, is that ok to write expectations like this - expect(e.style.MsFlexGrow || e.style.msFlexGrow).toBe('10');

[gaearon]

Might be a jsdom bug. Yes, I think this is fine since it depends on jsdom implementation.

[gaearon]

Thanks!