Ensure LModByPowerOf2I only gets environment when it deopts.

R=svenpanne@chromium.org
TEST=mozilla (with new --always-opt)

Review URL: https://codereview.chromium.org/423093009

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22803 ce2b1a6d-e550-0410-aec6-3dcde31c8c00