Small fixes to Throw and Mod Lithium instructions.

TEST=none
BUG=
R=ulan@chromium.org

Review URL: https://codereview.chromium.org/98603005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@18200 ce2b1a6d-e550-0410-aec6-3dcde31c8c00