Merge counters and v8-counters

BUG=none
LOG=n
R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/272433002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21185 ce2b1a6d-e550-0410-aec6-3dcde31c8c00