Fix a broken titleAttributes setter.
Fix a broken titleAttributes setter.

xuzhenguo/RDVTabBarController,kohtenko/RDVTabBarController,various/RDVTabBarController,SilverBulletZyp/RDVTabBarController,robbdimitrov/RDVTabBarController,blmyself/RDVTabBarController,gooc/RDVTabBarController,AlexanderMazaletskiy/RDVTabBarController,faimin/RDVTabBarController,xuanyi0627/RDVTabBarController,jiqiuyucool/RDVTabBarController,waynett/RDVTabBarController,wayne798/RDVTabBarController,justinyaoqi/RDVTabBarController,keyeMyria/RDVTabBarController,SummerHF/RDVTabBarController,spbreak/RDVTabBarController,bpc/RDVTabBarController