reference equality checks

[dotjoe]

Would there be a problem with checking for reference equality between objects or arrays? Please correct me if I'm wrong or if this has been answered already, but it looks like object and array keys are always iterated even when it might be the same reference between obj and newObj.

I was using this to diff fairly large objects that can sometimes share a lot of internal references so I felt like this could really speed that up as it wouldn't need to iterate every single nested property when it's the same reference.