Fixed an issue where notifications could visually overlap

While pulsing the notifications could overlap because they
were transparent. We're now making them not dimmable if they
are pulsing.

Fixes: 	129501157
Test: add 2 pulsing notifications, observe no overlap
Change-Id: Ic6db70a4d0dc202858834402e35a0e00fe631d68
4 files changed