Fix failing assertions on AppVeyor
Fix failing assertions on AppVeyor

These assertion pass on macOS, and they pass locally for me on Windows,
but they're failing on AppVeyor:

https://ci.appveyor.com/project/Atom/settings-view/build/493/job/eo9cabk62kwdq10g

By waiting for a condition to be true, instead of expecting it to be
_immediately_ true, we think we can resolve this flakiness.

Co-Authored-By: David Wilson <b23db01176e74adac76f54075bb2364df259e0b4@github.com>

atom/settings-view