of individual changes:
- Added infrastructure for custom stub caching.
- Push the code object onto the stack in exit calls instead of a
debug/non-debug marker.
- Remove the DEBUG_EXIT frame type.
- Add a new exit stub generator for API getters.
Review URL: http://codereview.chromium.org/330017
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3130 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
