https://developer.mozilla.org/en/DOM/window.location "Returns a Location object, which contains information about the URL of the document and provides methods for changing that URL. You can also assign to this property to load another URL." When using the inspector I see that I actually do get a Location object returned from window.location. However alert(window.location instanceof Location) throws: ReferenceError: Can't find variable: Location Occording to Wildfox, this is because there is no constructor for Location.
I can still reproduce this in Version 6.0.5 (8536.30.1)
This is fixed in at least Safari 9 seed 1, possibly earlier.
Thank you for following up! This is indeed fixed in shipping Safari versions already, not sure when exactly.