Regression(r174876): Use OILPAN empty destructor macros

Use OILPAN empty destructor macros as OILPAN is complaining about having a user
defined destructor. The destructor used to be protected by #if !OILPAN but I
removed this in r174876 inadvertently.

TBR=haraken@chromium.org

Review URL: https://codereview.chromium.org/302603005

git-svn-id: svn://svn.chromium.org/blink/trunk@174901 bbb929c8-8fbe-4397-9dbb-9b2b20218538