Fix typo in r19923 (bounds check offset propagation)

BUG=chromium:352929
LOG=n
R=ulan@chromium.org

Review URL: https://codereview.chromium.org/201303002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19969 ce2b1a6d-e550-0410-aec6-3dcde31c8c00