bugfix:z-index ignored with webkit overflow set to touch(-webkit-overflow-scrolling: touch)
bugfix:z-index ignored with webkit overflow set to touch(-webkit-overflow-scrolling: touch)

zhaoda/spa,luffy94608/spa,lin-chao/spa,luffy94608/spa,lin-chao/spa,wallaceyuan/spatest,npmcomponent/zhaoda-spa,zhaoda/spa