Fix the karma tests

I have honestly no idea what I'm doing here, just fixing the test failure. There might be a way better way to fix it.
Reset poll methods between tests.

Refs #3074.
reset plugins on every test
Merge pull request #1396 from djmitche/bug3074

Make tests pass with `-u`
Merge pull request #1393 from benallard/patch-4

Fix the karma tests