Fix scheduler for floating non-naked non-empty loops.

R=jarin@chromium.org
TEST=cctest/test-scheduler/NestedFloatingDiamondWithLoop

Review URL: https://codereview.chromium.org/709753002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25283 ce2b1a6d-e550-0410-aec6-3dcde31c8c00