Merged r14483 into trunk branch.

Fix bug in CompareNil IC

R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/14321005

git-svn-id: https://v8.googlecode.com/svn/trunk@14484 ce2b1a6d-e550-0410-aec6-3dcde31c8c00