Plus the fixes on top.

Reason: regresses benchmarks (JSBench) and perf (morejs).

TBR=rossberg@chromium.org
BUG=385404
LOG=N

Review URL: https://codereview.chromium.org/345513003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21882 ce2b1a6d-e550-0410-aec6-3dcde31c8c00