Add alternative syntax highlighting

[bradyt]

Dart is a somewhat fast moving language, with new language features both recent and planned.

I'd like to start the process of adding an alternative syntax highlighting implementation, for example, starting with just syntax highlighting of comments, and then adding from there.

Something like (setq dart-use-simpler-fontification t).

Potentially, haskell-mode is a good project to look at for ideas on this. I recall at least they have multiple implementations for indentation function for users to choose from.

If I can start over on a new "dart-mode-lite" without disrupting usage of the current implementation, I would appreciate an opportunity to break from some conventions and write a major-mode that emphasizes ease of maintenance and correctness.

[bradyt]

I think a nice attainable goal would be to implement an option like (setq dart-fontification 'dart-fontification-vim), and emulate the syntax highlighting found at https://github.com/dart-lang/dart-vim-plugin. That could create something of a small fixed target.