Make Logger::SuspectReadEvent extract the class name from the object.  This makes the lone caller cleaner, and also avoids a tiny bit of work in the default case of not running with --log-suspect.

Review URL: http://codereview.chromium.org/13655

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@943 ce2b1a6d-e550-0410-aec6-3dcde31c8c00