fsevents: remove dependency on go.assert

@ronbu @samjacobson @sdegutis I'm just starting to take a look at this project. It's quite over my head at the moment. :worried:

I'd like to create a project to log events for a set of actions, see https://github.com/go-fsnotify/fsnotify/issues/23. Eventually adding FSEvents support to fsnotify, see https://github.com/go-fsnotify/fsnotify/issues/11.

Help would be  most appreciated.