Before this change, bounds check elimination treated "<const> - x" as
"x - <const>".

R=yangguo@chromium.org
BUG=385054
TEST=test/mjsunit/regress/regress-385054.js
LOG=N

Review URL: https://codereview.chromium.org/339583003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21859 ce2b1a6d-e550-0410-aec6-3dcde31c8c00