Reapply r5603 with additional fix: use OS::StrNCpy instead of posix strncpy.

BUG=
TEST=

Review URL: http://codereview.chromium.org/3557010

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5605 ce2b1a6d-e550-0410-aec6-3dcde31c8c00