Allow stepping in functions called using CallFunction stub. When Debug::PrepareStep is called to prepare 'step in' and current code target is CallFunction stub, the debugger will find function being called on the expression stack and flood it with one shot breakpoints.Related Chromium issue: http://code.google.com/p/chromium/issues/detail?id=17978
Review URL: http://codereview.chromium.org/159703

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2745 ce2b1a6d-e550-0410-aec6-3dcde31c8c00