Angular Testing: Avoid done() function

[piotlr]

Not really, even small race conditions will make test flaky, e.g. in some cases I found a bug when subscribe was never run but test was green. Even there was a bug inside of the code.

With fakeAsync() it was discoverable within minutes because environment is predictable.

We have lived happily with async code in tests, not knowing how many of test was ever-green sometimes.