Fix issue with setters and their holders in accessors.cc

BUG=3462
LOG=Y
R=verwaest@chromium.org

Review URL: https://codereview.chromium.org/417793002

Patch from Erik Arvidsson <arv@chromium.org>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22606 ce2b1a6d-e550-0410-aec6-3dcde31c8c00