Don't report about extra quotes for key if its starts with zero

Here is problem.

```
// I have object with quoted and unquoted keys. 
var labels = {
    200204 : 'brown',
    EE1D19 : 'red',
    '0000CC' : 'blue',
    040001 : 'black, but undefuned :)'
};
// And I have array of keys which is always a Strings.
var stringKeys = [ '200204', 'EE1D19', '0000CC', '040001' ];

stringKeys.forEach(function(key) {
    // With key 040001 and similar I'll have undefuned. 
    console.log(labels[key]);
});
```

So I want to have quotes on keys like these.