Clear highlights and Find selection color when modal bar closes

This is my second attempt at #5239. First attempt is #5240.

Read this comment: https://github.com/adobe/brackets/pull/5240#issuecomment-24966396

@njx This is just a simple "close" event (first bullet from comment above). All it does is clear highlights and reset selection color. Worst case is that it's called twice.

<del>Regarding your second bullet, I don't see the case that needs to fixed. Everything seems to work correctly with this code. Please let me know.</del>

I played around with only clearing hignlighting and reset selection colors on "close" event, and I think I discovered the case for second bullet: when Find field is pre-populated and Enter is pressed before Find Next. So, it now handles both "closeOk" and "close".