No static assets when deploying to Heroku

[danielbonnell]

I followed the directions to set up a new WordPress instance on Heroku. After I deploy, I open the app in my browser and the setup page loads, but it is unstyled. There is no default theme. I've repeated the process 3x with the same result. I'm new to WordPress, so I don't know if I'm just missing an obvious step or if something is broken.