Fill out more of the Oilpan heap allocation implementation.

R=erik.corry@gmail.com, vegorov@chromium.org, wibling@chromium.org, zerny@chromium.org
BUG=

Review URL: https://codereview.chromium.org/104523005

git-svn-id: svn://svn.chromium.org/blink/trunk@164158 bbb929c8-8fbe-4397-9dbb-9b2b20218538