Suppress leak in DOMWrapperWorld()

BUG=340952
TBR=haraken@chromium.org
TEST=waterfall.sh match

Review URL: https://codereview.chromium.org/160133002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@250559 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 250559