I'm using "dev environment" and "dev server" distinctly. The dev environment is whatever I have on my computer, the dev server is a server that mirrors production. If there's a dependency on your dev environment that isn't on production, you'll catch it when you deploy to one of the dev servers. Same with the integration tests.
The problem is not that dev dependencies exist, the problem is that they might be undeclared or unrecorded. I have imagemagic on my dev machine, but if it isn't installed as part of the server setup script, then it won't be on the production server. The tests might run fine on a dev server that happens to have imagemagic on it, but fail in production.
>Integration tests run on the dev
If you run your integration tests in your dev environment, you might not catch some on the fly configuration changes or utility installations - undeclared dependencies.