Shorten JSXStyle generated prop names. Fix #530

[shYkiSto]

Updating JSXStyle generated prop names to a shorter version:

• styleId - > id
• css -> leveraging JSX's children (the css content will be enclosed into <JSXStyle></JSXStyle> element.

Transpiled version changes from:

// ...
React.createElement(JSXStyle, {
    styleId: "3463673021",
    css: ".test.jsx-3463673021{color:red;}"
});
// ...

to:

// ...
React.createElement(JSXStyle, {
    id: "3463673021"
}, ".test.jsx-3463673021{color:red;}");
// ....

While it helps reduce the final bundle size, it also resolves the incompatibility issue with styled-components (details)

[shYkiSto]

Hey @timneutkens @giuseppeg,

Just a kindly reminder in case you would like to, and have time to, review these changes :)

I would appreciate if we could publish new version that fixes the incompatibility issue with styled-components before the holidays(some kind of a Christmas present for everyone, if that matters)

Thank you!
Siarhei

[giuseppeg]

awesome thank you for the PR and sorry for the delay!

[giuseppeg]

@shYkiSto great PR! thank you so much for contributing and sorry for the slow response :)