Stop pretending we're AMD compatible

We're currently not AMD compatible. Inner anonymous modules doesn't work:

```javascript
define(function() {
  return something;
});
```

Even if we update the runtime to support it, we still need to fix the rewriting of dependencies since we don't rewrite them properly like we do with require:

```javascript
define(['toplevelname', '../relative'], function() {
  return something;
});
```

We're better off stop pretending to be AMD compatible, since universal modules will fallback to regular CommonJS instead of failing to load.