Fixes cirular references detection in PhantomReporter's stringify function.

The logic which was in place to convert array-like objects to arrays prevented the circular reference detection to work properly for arrays and array-like objects.

`cache.indexOf(value)` can never be `> -1` since `value` is `tempArray`, which was just created.

Here is an example of the behavior (before and after the fix): http://jsbin.com/abanur/3/edit

The call to the original function (`stringify`) creates a *"too much recursion"* error or *"Range Error: Stack size exceeded"*.