The icons that includes in the `_svg.js` files are generated from the corresponding icon.

They are generated by the following:

```bash
cp src/icons/<name>.svg src/icons/<name>-1em.svg
node_modules/.bin/svgo src/icons/<name>-1em.svg
node buildtools/svg-viewbox-cmd.js src/icons/<name>-1em.svg 'height=1em'
```