use dispatch_sync to guard textsHeightCache_
use dispatch_sync to guard textsHeightCache_

chzyer-dev/Karabiner,runarbu/Karabiner,chzyer-dev/Karabiner,muramasa64/Karabiner,tekezo/Karabiner,wataash/Karabiner,muramasa64/Karabiner,runarbu/Karabiner,tekezo/Karabiner,tekezo/Karabiner,wataash/Karabiner,runarbu/Karabiner,astachurski/Karabiner,miaotaizi/Karabiner,astachurski/Karabiner,astachurski/Karabiner,wataash/Karabiner,wataash/Karabiner,muramasa64/Karabiner,miaotaizi/Karabiner,e-gaulue/Karabiner,e-gaulue/Karabiner,e-gaulue/Karabiner,miaotaizi/Karabiner,chzyer-dev/Karabiner,e-gaulue/Karabiner,astachurski/Karabiner,miaotaizi/Karabiner,muramasa64/Karabiner,chzyer-dev/Karabiner,tekezo/Karabiner,runarbu/Karabiner