Oilpan: tighten DISALLOW_ALLOCATION so it does not allow inline
allocation by user-defined placement new operators.

Removing the placement new operators will lead to redefinition errors
if a class is marked as DISALLOW_ALLOCATION or STACK_ALLOCATED
and at the same time defines placement new operators.

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

Review URL: https://codereview.chromium.org/199733009

git-svn-id: svn://svn.chromium.org/blink/trunk@169642 bbb929c8-8fbe-4397-9dbb-9b2b20218538