[WEEX-133][iOS] support word-wrap on iOS when drawing text
[WEEX-133][iOS] support word-wrap on iOS when drawing text

 support word-wrap on text component, according to w3c rules, word-wrap
maybe normal or word-break value, and normal will just clip character, and
word break will break a new line.

w3c document: https://developer.mozilla.org/en-US/docs/Web/CSS/overflow-wrap

try case: http://dotwe.org/vue/5460408a9159fd13168f64bf0b046c4b

Bug:133

miomin/incubator-weex,alibaba/weex,cxfeng1/incubator-weex,cxfeng1/incubator-weex,miomin/incubator-weex,acton393/incubator-weex,erha19/incubator-weex,erha19/incubator-weex,MrRaindrop/incubator-weex,KalicyZhou/incubator-weex,Hanks10100/incubator-weex,erha19/incubator-weex,acton393/incubator-weex,MrRaindrop/incubator-weex,Hanks10100/incubator-weex,Hanks10100/incubator-weex,alibaba/weex,erha19/incubator-weex,alibaba/weex,acton393/incubator-weex,KalicyZhou/incubator-weex,miomin/incubator-weex,acton393/incubator-weex,alibaba/weex,Hanks10100/incubator-weex,miomin/incubator-weex,Hanks10100/incubator-weex,Hanks10100/incubator-weex,miomin/incubator-weex,erha19/incubator-weex,cxfeng1/incubator-weex,miomin/incubator-weex,alibaba/weex,acton393/incubator-weex,KalicyZhou/incubator-weex,MrRaindrop/incubator-weex,alibaba/weex,acton393/incubator-weex,MrRaindrop/incubator-weex,cxfeng1/incubator-weex,erha19/incubator-weex,cxfeng1/incubator-weex,MrRaindrop/incubator-weex,cxfeng1/incubator-weex,Hanks10100/incubator-weex,KalicyZhou/incubator-weex,erha19/incubator-weex,miomin/incubator-weex,acton393/incubator-weex,acton393/incubator-weex,KalicyZhou/incubator-weex,Hanks10100/incubator-weex,erha19/incubator-weex,KalicyZhou/incubator-weex,miomin/incubator-weex,MrRaindrop/incubator-weex,alibaba/weex