Make sure tagged binary op instructions change new space promotion.

BUG=
R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/194883003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19790 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Do not overwrite already optimized code.

BUG=
R=ulan@chromium.org

Review URL: https://codereview.chromium.org/189603006

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19791 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Enable concurrent sweeping.

BUG=
R=jochen@chromium.org

Review URL: https://codereview.chromium.org/166683002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19792 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Revert "Mark mjsunit/string-case as flaky."

This reverts r19760 since the issue has been fixed in r19755.

R=dslomov@google.com, dslomov@chromium.org
BUG=v8:3208
LOG=N

Review URL: https://codereview.chromium.org/194823002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19793 ce2b1a6d-e550-0410-aec6-3dcde31c8c00