functions (as an alias for calling the exec method).  For
compatibility make call_regexp the default and remove the flag.

Review URL: http://codereview.chromium.org/155453

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2451 ce2b1a6d-e550-0410-aec6-3dcde31c8c00