This moves the two remaining browser tests in toolkit/mozapps/downloads/tests to
an xpcshell test and a chrome test. The reason for this change is to remove the
dependency of the browser from download manager tests since it is a toolkit
component.
This version unregisters the factory that we register to override the prompt
service in test_bug_412360.xul so we no longer leak.
r=gavin
--HG--
rename : toolkit/mozapps/downloads/tests/browser/browser_bug_406857.js => toolkit/components/downloads/test/unit/test_bug_406857.js
rename : toolkit/mozapps/downloads/tests/browser/browser_bug_412360.js => toolkit/mozapps/downloads/tests/chrome/test_bug_412360.xul
