Fix bug 1047018: Track successful log in/out

Yep. I'll go ahead and make the update.

At the same time, and to be pedantic, I've thought quite a bit about this kind of thing. I tend not to worry about language-level performance because (1) it's negligible compared to the performance wasted by unused features, unneeded assets, and other high-level problems and (2) because I prefer not to sacrifice code quality for problems that should be addressed by implementers&mdash;it's my view that programmers should write clear code, and that implementers should be responsible for making clear code run efficiently.

https://twitter.com/aral/status/474453038900727808

But it also doesn't hurt much, aside from readability issues, so I'll go ahead and make the change.