Kept the previous message handler API to avoid breaking clients depending on it.

The new message handler API uses a new name ending with 2.
Review URL: http://codereview.chromium.org/100158

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@1816 ce2b1a6d-e550-0410-aec6-3dcde31c8c00