Morph and "whenever ... deals damage"

If damage from a face-down creature is on the stack, and that creature
is turned face-up before it resolves, does "whenever ~ deals damage"
trigger?

For example:
Player A declares a face-down creature as an attacker, and player B does
not block. After combat damage goes on the stack (all assigned to
Player B), player A pays the morph cost and turns Raven Guild Master
face-up.

When the damage resolves, does Player B "mill" 10 cards?


Raven Guild Master 
1UU  
Creature ‹ Wizard Mutant  
1/1  
Whenever Raven Guild Master deals combat damage to a player, that player
removes the top ten cards of his or her library from the game.
Morph 2UU (You may play this face down as a 2/2 creature for 3. Turn it
face up any time for its morph cost.)