Bug 1251916 - Use standard JavaScript features in toolkit/components/passwordmgr to pass eslint checks: enable eslint. r=MattN

MozReview-Commit-ID: F8nvRExCbff

--HG--
extra : rebase_source : 07d5a9136de52a2af8f8591884f564f7c3284299
extra : amend_source : 5762ef9d2ddc1d1023a68a411a2f5584d0ee15e1

.eslintignore

@@ -180,7 +180,6 @@ toolkit/modules/tests/xpcshell/test_task.js
 
 # Not yet updated
 toolkit/components/osfile/**
-toolkit/components/passwordmgr/**
 
 # Uses preprocessing
 toolkit/content/widgets/videocontrols.xml