Turn on concurrent sweeping.

BUG=
R=jarin@chromium.org

Review URL: https://codereview.chromium.org/230733002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@20612 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
ARM64: Use pair memory access in deoptimizer entry

BUG=
R=ulan@chromium.org

Review URL: https://codereview.chromium.org/228573003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@20613 ce2b1a6d-e550-0410-aec6-3dcde31c8c00