Fix Tree-Sitter JavaScript highlighting for JSX file

[ryanolsonx]

This should also apply to standard JavaScript files, but specifically,
JSX syntax highlighting has been struggling.

Description of the Change

As noted in #100, there's a lot of highlighting missing when Tree-Sitter is enabled for JavaScript. The focus of this PR is to address many of those changes and provide much needed color. It doesn't fix everything perfectly. In atom/language-javascript, there's an issue (atom/language-javascript#618) that covers adding highlighting back for language keywords (such as this and super).

Before

After

Alternate Designs

None.

Benefits

JavaScript highlighting is improved.

Possible Drawbacks

None.

Applicable Issues

#100

[ryanolsonx]

@simurai Any thoughts on this?

[simurai]

As noted in #100, there's a lot of highlighting missing when Tree-Sitter is enabled for JavaScript.

I think there is still some work in progress getting the Tree-sitter syntax highlighting more in sync with Textmate's. But we can still merge this now since it looks already much better.

@ryanolsonx Thanks.. 🙇