We've improved the startup IO situation in bug 887889 by not synchronously
initializing a connection to the contentprefs db. However, this means
we are loading Sqlite.jsm earlier than we were, which isn't ideal and
can be avoided. However, this isn't completely trivial so I'd like to
move this work to a follow-up.
MozReview-Commit-ID: 6Em0rN26Qj3