Reland "Fix scheduler to correctly schedule nested diamonds".

Reland fix: Consume less memory.

R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/636233006

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24597 ce2b1a6d-e550-0410-aec6-3dcde31c8c00