Swich to the new CpuProfiler api that returns non-const CpuProfile

BUG=v8:3213

Review URL: https://codereview.chromium.org/196423009

git-svn-id: svn://svn.chromium.org/blink/trunk@169427 bbb929c8-8fbe-4397-9dbb-9b2b20218538