Block/line comment trigger

I was just noticing that the standard `cmd+/` keybinding for commenting out a line, seems to have a glitch. It appears that the action is firing, as you can see a brief flash of the appropriate comment characters being inserted, but then those characters are immediately removed.

Also worth noting is that with the `option` modifier (for inserting a block comment), the comment is inserted, but not removed like with the line comment. However, it seems the action is fired twice, as a second block comment is nested inside the first.

The offending filetypes that I have noticed this behavior in are `CSS` and `JavaScript`.

I hope this is enough info to reproduce the bug!

Thanks for the wonderful work on this editor btw ;)