Backed out changesets 917205c79822 and e9ef1f1aa47d (bug 841413) for causing mochitest-chrome failure.

Failure is:
ERROR TEST-UNEXPECTED-FAIL | chrome://mochitests/content/chrome/toolkit/components/passwordmgr/test/test_privbrowsing_perwindowpb.html | uncaught exception - TypeError: normalWindowIframe is null at chrome://mochitests/content/chrome/toolkit/components/passwordmgr/test/test_privbrowsing_perwindowpb.html:266