Make gremlins.js a dev dependency

Make gremlins.js a dev dependency

Status: **Opened for visibility**

Reviewers: @scalvert 


## Changes
- make gremlins.js a dev dependency instead of a dependency
Depends how we want to do our device support. Firefox hasn't needed box-sizing prefixing for the past six versions so I think we're safe to lose it but we should update our Device table to reflect that.