Delete useless --loop-weight flag

killing a static variable in the process.

BUG=chromium:333871
LOG=N
R=ulan@chromium.org

Review URL: https://codereview.chromium.org/131223009

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@18587 ce2b1a6d-e550-0410-aec6-3dcde31c8c00