babel-runtime & transform-runtime & babel-polyfill

 学习mark

babel转译后存在重复性代码 

babel-runtime可以解决重复性代码，

babel-transform-runtime自动检测依赖

babel-polyfill功能最全

https://segmentfault.com/q/1010000005596587

https://www.zhihu.com/question/49382420

http://blog.csdn.net/a324539017/article/details/52824189