Instructions that have side effects can never have EmitAtUses() true.
These instructions (CmpTAndBranch, InstanceOfAndBranch) are therefore
never generated and can therefor be safely removed.
Review URL: http://codereview.chromium.org/7031074

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@8220 ce2b1a6d-e550-0410-aec6-3dcde31c8c00