While the original "no focused webview" bug (with the first test after spawning
qutebrowser) from #1183 was fixed, we still had a case where the next test
after ":fake-key sending key to the website with other window focused" failed,
presumably because the inspector was still focused, e.g. here:
http://qutebrowser.org:8010/builders/osx/builds/1175/steps/tests/logs/stdio
This hopefully fixes this by properly waiting until the inspector is gone.
