stabilize firefox test runner to use cfx run.

This stabilizes the firefox test tooling for our integration test.  That is now stable despite the latest firefox, but doesn't change underlying tests.

It gets oAuth to pass more but it still seems flaky
rtcpeerconnection is failing
social integration double is timing out sometimes. (flaky)

If the tab is still foreground or still has this or other progress listeners attached at the point it is removed, errors occur.