Runtime throws error in Safari 5

Safari 5 doesn't like the Traceur runtime. In particular, it chokes on the following code:

```
var modules = {
  get '@name'() {
    return NameModule;
  },
  get '@iter'() {
    return IterModule;
  },
}
```

The error received (from minified version) is:

```
main.js:1SyntaxError: Unexpected string "@name"
```

Safari 5 supports ES5, so I'd expect it to be compatible.