Vales not correctly hydrated in getAllProperties

I don't have a reduced testcase yet, but I have the situation where some values are hydrated, others are not. Then I call ```getAllProperties()``` and expect to get them all. Lets say properties (by index) 1, 2, 3, 5, 6 are hydrated, 4 is not. The array you get in return is:

[object Object], [object Object], [object Object],,[object Object], [object Object]

The problem is a check like this:
```javascript
if (!this._properties && this._properties.length !== jCalLen) {
...
}
```

Since the 6th element of the array is already there, the length of the array is 6, even though element 4 is missing.

The quickest possible (js1.6) cure is to use ```this._properties.filter(Boolean).length```, but this might be a performance issue.