This quest is no longer available within the game.
Speak with Stone Guard Kurjack.
With all his usual grace, Warchief Garrosh has kindly requested your presence in Ragefire Chasm to help retake it from the Searing Blade. Apparently, his reinforced city isn't as impenetrable as he thought.
Go speak with Stone Guard Kurjack just inside Ragefire, I'm sure he'll be glad to have competent help.