Fix XCode project.

This is temporary. The XCode project will be deleted soon once support for generating it with gyp is in place.

R=sgjesse@chromium.org
BUG=
TEST=

Review URL: http://codereview.chromium.org/6904165

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@7740 ce2b1a6d-e550-0410-aec6-3dcde31c8c00