Add an LSan suppression for leak in WebCore::V8GCController::collectGarbage.

BUG=46571
TBR=glider@chromium.org

Review URL: https://codereview.chromium.org/47463004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@231266 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 231266