Reland: Use OwnPtrs for heap contains cache and persistent anchor. We were leaking the HeapContainsCache.

R=oilpan-reviews@chromium.org, vegorov@chromium.org, haraken@chromium.org
BUG=348629

Review URL: https://codereview.chromium.org/189853003

git-svn-id: svn://svn.chromium.org/blink/trunk@168734 bbb929c8-8fbe-4397-9dbb-9b2b20218538