I just upgraded from version 15.57 to 15.59, and now the object browser is no longer able to load the content document for Chrome. All it says is "Error: Exception Occured". I tried it on another mac...
We use the Script.eval functionality of contentDocument, and experienced the same issue where it stopped working in version 15.58 (and also 15.59). I opened a case over a week ago. Perhaps open a case with them as well.