We've replaced SharedPersistent with ScopedPersistent or ScriptValue before, but a couple of SharedPersistents are remaining. So this CL replaces them.

Ideally we want to remove SharedPersistent though.

Review URL: https://codereview.chromium.org/146523002

git-svn-id: svn://svn.chromium.org/blink/trunk@165751 bbb929c8-8fbe-4397-9dbb-9b2b20218538