Also:
- move constructor name getter near similar class name getter method;
- if the constructor is not present, use 'Object', as for class name, this eliminates a special case.

Review URL: http://codereview.chromium.org/202018

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2859 ce2b1a6d-e550-0410-aec6-3dcde31c8c00