Importing internal dependencies

Nobody has claimed this yet.

I am creating a new drawing mode. To avoid reinventing the wheel I would like to reuse some functions that were already implemented in:
```

@mapbox/mapbox-gl-draw/src/lib/common_selectors
@mapbox/mapbox-gl-draw/src/lib/double_click_zoom
```
I am using create-react-app and if I try to import any of them and build my project, I have the minification issue:

```bash
Failed to minify the code from this file:
./node_modules/@mapbox/mapbox-gl-draw/src/lib/double_click_zoom.js:2
```
I am using:
**mapbox-gl-js 0.44.2**:
**mapbox-gl-draw 1.0.7**:

I could send a PR if I get a better understanding how to solve this.

Start by inspecting src/lib/common_selectors and src/lib/double_click_zoom, then reproduce the create-react-app build failure involving double_click_zoom.js. Determine what change is needed so these internal dependencies can be imported without the minification error; done means the project builds successfully with those imports.

Written by the indexing model from the issue text.