Bug 1061215 - [Messages][Refactoring] Improve handling of remaining chars counter. r=schung

globally, I'd like to have different hooks for CSS and JS.

For CSS, try to have classes only.
For JS, we could have IDs, or different classes (prefixed by js-) (like I did for the sim indicator in the send button)

The goal is to have some conventions that would let us read more easily our markup and know more easily the effects of some changes.

What do you think?