Make function-level static Persistent handles leak instead.

We cannot have Persistent (as opposed to Persistent*) as function-level statics,
since they'll cause exit-time dtors when we make Persistent auto-Dispose in the
dtor.

BUG=236290

Review URL: https://chromiumcodereview.appspot.com/19688009

git-svn-id: svn://svn.chromium.org/blink/trunk@154643 bbb929c8-8fbe-4397-9dbb-9b2b20218538