Fix bug in compilation of calls with proxy receivers.

R=kmillikin@chromium.org,ager@chromium.org
BUG=
TEST=

Review URL: http://codereview.chromium.org/7237050

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@8630 ce2b1a6d-e550-0410-aec6-3dcde31c8c00