can't build at create-react-app boilerplate

## version
* awaiting v3.0.0
* create-react-app v1.0.5

`yarn run start` can work fine
`yarn run build` will get a error
```bash
static/js/main.ab319118.js from UglifyJs
Unexpected token operator «*», expected punc «(» [./~/awaiting/dist/awaiting.common.js:80,0][static/js/main.ab319118.js:9708,47]
```

Reproduce the failure with `yarn run build` using the reported create-react-app v1.0.5 setup, then inspect `awaiting/dist/awaiting.common.js` around line 80 and the UglifyJs error. Compare this with the successful `yarn run start` path; done means the production build completes without the reported unexpected-token error.

Written by the indexing model from the issue text.