A pointer comparison on the effect path states is not sufficient to
guarantee termination; we really need to check the actual nodes to
make sure we terminate properly, similar to what BranchElimination
does.

R=jarin@chromium.org
BUG=v8:5161

Review-Url: https://codereview.chromium.org/2112463002
Cr-Commit-Position: refs/heads/master@{#37389}