Bug 876758 - [sms] normal messages are incorrectly considered class-0 messages when clicking the notification and the app is not running r=gnarf

We were testing the type of SMS/MMS but we don't have that information. Instead,
we know when a notification is related to a class-0 message, so let's use that
instead.
(cherry picked from commit 33abecaf661a4bb7440726c8809748368cc9af60)