[WEEX-511][iOS] Fix debug log may crash when there is a retain cycle in the object
[WEEX-511][iOS] Fix debug log may crash when there is a retain cycle in the object

miomin/incubator-weex,KalicyZhou/incubator-weex,acton393/incubator-weex,Hanks10100/incubator-weex,Hanks10100/incubator-weex,Hanks10100/incubator-weex,acton393/incubator-weex,Hanks10100/incubator-weex,KalicyZhou/incubator-weex,alibaba/weex,acton393/incubator-weex,alibaba/weex,miomin/incubator-weex,acton393/incubator-weex,Hanks10100/incubator-weex,alibaba/weex,miomin/incubator-weex,KalicyZhou/incubator-weex,alibaba/weex,miomin/incubator-weex,miomin/incubator-weex,KalicyZhou/incubator-weex,acton393/incubator-weex,miomin/incubator-weex,KalicyZhou/incubator-weex,miomin/incubator-weex,acton393/incubator-weex,Hanks10100/incubator-weex,alibaba/weex,Hanks10100/incubator-weex,acton393/incubator-weex,Hanks10100/incubator-weex,alibaba/weex,acton393/incubator-weex,KalicyZhou/incubator-weex,miomin/incubator-weex,alibaba/weex