chore(dialog): update to remove assumption of backdrop shown by default
chore(dialog): update to remove assumption of backdrop shown by default

Q-Free-OpenRoads/ng2-material,Q-Free-OpenRoads/ng2-material,mailiam/ng2-material,paulussup/ng2-material,mailiam/ng2-material,mailiam/ng2-material,parmalatinter/ng2-material,paulussup/ng2-material,dmacfarlane/ng2-material,parmalatinter/ng2-material,paulussup/ng2-material,Q-Free-OpenRoads/ng2-material,dmacfarlane/ng2-material,Q-Free-OpenRoads/ng2-material,dmacfarlane/ng2-material,parmalatinter/ng2-material