Fixes #2940: Unable to remove smart parameter with long name

> @lzap the Rails limitation is still problematic, @eLobato doesn't see the text truncated.
> I think it might be better to have the close button pushed down then the text not truncated correctly and maybe someone will know how to fix the css.
> What do you think?

Hmmm it worked for me:

    very_very_very_very_very_very_very_very_very_long_option

Chrome stable.

Unfortunately I have *no* idea how to do this in pure CSS :-(

I'd rather stick to what we have here, maybe if you limit it to 10-15
characters that would help. I know that's not too many, but we can add
mouse hover with full title too.

-- 
Later,
 Lukas #lzap Zapletal